- How to Fix P0171 and P0174 While inspecting the intake boot thoroughly, another option is to stop at the MAF sensor itself. MAF sensors can get dirty or oiled and send out a false signal, but usually this is also indicated by a MAF trouble code as well.
What causes code P0171 and P0174?
Code P0171 indicates Bank 1 of the engine has a lean fuel mixture. P0174 indicates Bank 2 of the engine has a lean fuel mixture. P0171 is triggered by the engine bank 1 “upstream” oxygen sensor and P0174 is triggered by the engine bank 2 “upstream” oxygen sensor.
How do I fix code P0174?
What repairs can fix the P0174 code?
- Replacing mass air flow sensor.
- Cleaning mass air flow Sensor.
- Replacing faulty oxygen sensor.
- Replacing PCV valve.
- Replacing vacuum line.
- Replacing EGR valve.
- Replacing brake booster.
- Replacing valve cover gasket.
Can a bad PCV valve cause code P0171?
The most common causes of the P0171 code are vacuum or intake leaks, low fuel pressure, faulty PCV valve, or a faulty MAF sensor. Other things can also cause the P0171 code.
Can a MAF sensor cause P0171?
Problems with the mass air flow (MAF) sensor causing the code P0171 are fairly common in many vehicles. Sometimes the mass air flow sensor just gets dirty and gives false air flow readings causing the engine to run lean.
Can a dirty air filter cause a P0174 code?
A plugged Fuel Filter or poorly functioning Fuel Pump can set the P0174 code. The computer hears (accurately) from the Oxygen Sensor that the Fuel Mixture is too lean so the computer keeps increasing the amount of fuel being delivered into the combustion chambers.
Can I drive with P0171 code?
It is okay to drive a vehicle with P0171 for a short period of time, but driving with this code for an extended period of time can overheat the engine and cause internal engine damage.
What causes P0171 and P0174 codes Ford?
COMMON CAUSE: A DIRTY MAF SENSOR One of the most common causes of Ford P0171 and P0174 lean codes is a dirty mass airflow (MAF) sensor. The MAF sensor can also be contaminated by fuel vapors that back up through the intake manifold and throttle body when the engine is shut off.
Can bad spark plugs cause P0171?
Not likely. A P0171 ( too lean, Bank 1 ) code is most often caused by a vacuum leak downstream from the MAF sensor or a malfunctioning MAF sensor. Bad spark plugs could actually cause the opposite code ( too rich, bank 1).
How do I reset my P0171 code?
Fixing a Check Engine Light (P0171)
- Step 1: Purchase a OBD 2 Bluetooth Scanner.
- Step 2: Insert the Scanner Into the OBD 2 Port of Your Car.
- Step 3: Run a Diagnostic Scan.
- Step 4: P0171.
- Step 5: Removing the Mass Air Flow Sensor.
- Step 6: The MAF Sensor.
- Step 7: Clean the Sensor.
- Step 8: Clear the Code.
Can I drive with a P0174 code?
It is okay to drive a vehicle with P0174 for a short period of time, but driving with this code for an extended period of time can overheat the engine and cause internal engine damage.
How do I fix code po430?
What repairs can fix the P0430 code?
- Replacing the catalytic converter.
- Diagnosing and repairing the engine misfire.
- Replacing the fuel injector.
- Repairing any mechanical damages in the engine.
- Replacing the oxygen sensor.
- Repairing or replacing the exhaust replaced.
Can a bad 02 sensor cause a P0171 code
You probably know that the answer the questions is — no! A P0171 or P0174 lean code with an O2 sensor reading lean all the time mean — well, several things. The real problem may not be a bad O2 sensor, but possibly be an engine vacuum leak, low fuel pressure or dirty fuel injectors that are causing the engine run lean.
Can a dirty air filter cause a P0171 code?
If the filter is clogged or excessively dirty, this is enough to impede or restrict the air flow, hence resulting in a lean running condition. Besides a dirty air filter, the P0171 code can also be blamed on a dirty or faulty MAF sensor and a clogged fuel filter.
What are the signs of a bad PCV valve?
Bad PCV Valve Symptoms
- Check Engine Light. The most common and most noticeable sign of all bad PCV valve symptoms is probably a check engine light on your dashboard.
- High Idle RPM/Rough Idle.
- Lean/Rich Mixture.
- Rough Acceleration.
- Increased Oil Consumption & Oil leaks.
- White/Black/Blue Smoke from the Exhaust.
What Do P0171 and PO174 Mean?
The code P0171 indicates that the fuel mixture in Bank 1 of the engine is too lean. P0174 indicates that the fuel mixture in Bank 2 of the engine is too lean. Engine Cylinder 1 is located on the same side of the engine as Engine Bank 1. Engine Bank 2 is located on the opposite side of the engine from Engine Bank 1. It may be necessary to consult a firing order and cylinder placement diagram in order to determine whether side of the engine is Bank 1 or Bank 2. P0171 is activated by the ‘upstream’ oxygen sensor in engine bank 1, and P0174 is triggered by the ‘upstream’ oxygen sensor in engine bank 2, respectively.
The symptoms and causes will assist you in determining the specific nature of the problem and how to resolve it.
Upstream sensors, or those located close to the engine and before the catalytic converter, are referred to as Sensor 1.
These upstream sensors check that the proper air/fuel ratio is being introduced into the engine cylinders by detecting the oxygen levels in the exhaust gases that are being expelled from the engine.
- A high voltage measurement that remains constant suggests a rich fuel combination with insufficient oxygen.
- In this case, the ideal ratio is 14.7:1.
- A P0171 or P0174 error code is generated when your powertrain/engine control module receives a measurement that indicates there is too much oxygen present and the ratio is improper.
- It is crucial to note that the very nature of the oxygen sensor delivering these codes, in the absence of any other oxygen sensor failure codes, indicates that the sensor is functioning as it should be.
- In a nutshell, the engine is running lean, and the computer is unable to determine why.
P0171 and P0174 Symptoms
There are several cases where engine performance concerns do not manifest themselves. Some lean circumstances, on the other hand, might cause your car to have the following performance issues:
- Intense or hesitant acceleration
- Misfires (which will generally result in the generation of a misfire code)
- Low power
- Rough starting and idling. Spark knock or explosion.
Intense or hesitant acceleration; Misfires (which will often result in the setting of a misfire code); Spark knock or explosion; reduced power; rough idle; and other issues
There are a variety of minor and significant fixes that might result in this problem. Start with the simplest difficulties and work your way through the list until you’ve identified the root cause of your error code. Lean situations are frequently created by air entering the system in an area where it cannot be seen or measured. The intake system, which is normally behind the MAF sensor, and a vacuum leak anywhere in the intake system are the two most likely culprits for this. Starting with the intake boot that connects the MAF to the throttle body, look for any leaks.
- Check all of the vacuum hoses on the engine for cracks or breaks in the hose before continuing.
- This is a common sign of a large vacuum leak and should be addressed immediately.
- If nothing appears to be wrong here, it is possible that there are other, more serious problems going on.
- This will result in a significant vacuum leak and the onset of a lean situation.
It is crucial to remember that, in most cases, fuel-related difficulties such as these will also result in a misfire code being displayed – either randomly or on specific cylinders.
How to Fix P0171 and P0174
Minor or large repairs might be the source of this problem in many cases. Work your way through the simplest difficulties first, then progress to the more difficult ones until you have determined the source of your problem code. Low-pressure circumstances are frequently generated by air entering the system in an area where it cannot be detected. The intake system, which is normally behind the MAF sensor, and a vacuum leak anywhere in the intake system are the two most likely culprits for this problem.
- Cracks, loosened hose clamps, and any other openings where air may get in should all be checked out.
- During operation of the engine, pay close attention to the sound of air being sucked through a break, since this might indicate a large vacuum leak.
- The possibility of additional serious concerns developing if nothing appears in this section should not be overlooked.
- Due to the vacuum leak, the system will get overloaded and go into lean mode.
- However, it is crucial to understand that, in most cases, fuel-related problems such as these will also result in a misfire code being displayed — either randomly or on specific cylinders.
P0171 and P0174: What it Means When These Codes are Together
P0171 and P0174 are both diagnostic codes that indicate that an alean situation is present in the vehicle. They are some of the most often seen OBD II codes on their own. When they are present simultaneously, it signifies that the entire engine is operating at a low RPM setting.
Both of these codes are generic, which means that they have the same meaning regardless of the vehicle in which they are displayed or used in.
- In this case, the P0171 code indicates that the side of the engine with the first cylinder (Bank 1) is running lean
- In other words, the fuel trim system is running lean. A P0174 code indicates that the fuel trim system on the side of the engine with the first cylinder (Bank 2) is operating at an excessively lean setting. This code is not accessible on inline engines since there is only one ‘bank’ of cylinders on these engines. The term ‘lean condition’ refers to the fact that the engine is drawing in too much air in comparison to the amount of fuel present. There are a variety of factors that might contribute to a vehicle becoming lean. A vacuum leak, an EGR problem, or a malfunctioning mass airflow sensor are all possibilities, as is a lack of fuel (poor injectors, a faulty fuel pump, a clogged fuel filter, or a faulty fuel pressure regulator).
When the air/fuel combination in the vehicle becomes too lean, the codes P0171 and P0174 are shown. When the oxygen sensors detect that there is insufficient oxygen in the exhaust, they both throw the error. The engine then makes modifications to compensate and generates these codes, which cause the service engine soon light to illuminate on the dashboard. When both of these codes arise at the same time, it is more than likely that the intake manifold gasket is the source of the problem, rather than the engine.
Some of these codes aren’t related with poor driving conditions all the time.
For the vast majority of individuals, the appearance of the service engine soon light is the first indication that anything is amiss. When you have codes P0174 and P0171, you will often experience the following symptoms, which indicate that something is amiss.
- Fuel mileage-depending on how much the air fuel combination has altered, it may or may not suffer a reduction. Misfire – If the air fuel combination has deviated too far from the manufacturer’s specifications, the vehicle may misfire or perform poorly. This is frequently seen in conjunction with P0300. If you have this code in addition to P0171 and P0174, disregard the P0300 code. It should go away once you’ve resolved the problem with the air/fuel combination. Car Idling Issues — When the air/fuel mixture is changed, the vehicle might idle erratically while the computer adapts in order to keep the engine operating.
The following are the most often seen causes of P0171 and P0174. The most prevalent causes of vacuum leaks are intake manifold leaks (especially at the intake manifold) and the MAF sensor.
The most typical reason for the P0174 or P0171 codes to appear in most cars is a vacuum leak, which is discussed more below. Take a look around to see if you can locate the source of the vacuum leak. Here’s a wonderful YouTube video that demonstrates how to locate a vacuum leak: A very high probability of the intake manifold leaking exists if the engine allows unmetered air into the engine. However, the leak might be everywhere. A decent scan tool can also assist you in determining whether or not there is a vacuum leak.
However, when you power the engine, the fuel trim should decrease to around 0.
Mass Air Flow Sensor
The mass air flow sensor is responsible for calculating the volume of air that enters the engine. The air fuel mixture will be off if it has failed and the P0174 and/or P0171 codes will be shown as a result. It will be situated in the space between the air filter and the throttle body on the vehicle. It’s not difficult to locate. It will be equipped with a wire harness that will be connected to it. When it comes to the MAF sensor malfunctioning, filthy air is the number one cause of the problem.
It will allow unfiltered air to enter, and it will soon contaminate the MAF sensor to the point that it will no longer function correctly.
In any case, the most important thing is to clean the MAF sensor using a MAF sensor cleaning.
It has a high sensitivity.
The EGR system’s purpose is to recycle exhaust gases in order to produce cleaner emissions. If it has failed, you may see these codes because it will cause the vehicle’s vacuum level to be out of whack.
Bad Fuel Injectors
If you have one or more fuel injectors that have failed, this can almost likely result in the air/fuel combination becoming contaminated. P0174 and P0171, on the other hand, imply that BOTH sides of the engine are operating in a lean state. One faulty fuel injector would be enough to cause one of those codes to appear. Both codes might be caused by multiple defective fuel injectors on both sides of the engine; however, this is highly improbable to occur. If you have more than one cylinder-related misfire code (such as P030X, where X represents the misfiring cylinder), it is probable that you have more than one faulty injector in your vehicle.
Fuel Pump/Fuel Filter
Modern fuel-injected engines need a high level of fuel pressure in order to adequately atomize the gas. If the fuel pressure is not as high as it should be, atomization will not occur effectively, and the appropriate air/fuel combination will not be obtained.
On the subject, here’s a terrific YouTube video to watch. This individual delves deeply into the problem and may be quite helpful in identifying the source of the error code.
Hope this helps you figure out why your automobile or truck is emitting the P0171 and P0174 error codes! If you have any suggestions for how to make this post better, please feel free to leave a comment below.
Fix P0171 code, P0174 code
First and foremost, let’s define what a P0171 code is. The official definition is P0171 System Is Too Lean (System Is Too Lean) (Bank 1). When it occurs on a V-6 or V-8 engine, it is frequently accompanied with the P0174 System too Lean code (Bank 2). Crankshaft bank 1 of a V-engine is the bank that contains cylinder 1. A P0171 code and a P0174 code are the most often encountered issue codes across all automobile manufacturers. Among the most often encountered issue codes that cause a vehicle to fail emissions testing, they are among the ‘Top Ten.’ It is impossible to have any surplus fuel or oxygen in the exhaust when the air/fuel combination is calculated correctly and burnt properly in the cylinders.
What causes a P0171 code or P0174 code?
Before we go any further, let’s define what a P0171 code actually means. P0171 System is Too Lean is the official definition (Bank 1). The P0174 System too Lean code is frequently seen on V-6 and V-8 engines (Bank 2). In a ‘V’ engine, bank 1 is the bank that contains cylinder 1. Among the most prevalent issue codes for all automobile brands are the P0171 and P0174 codes. They are among the ‘Top Ten’ fault codes that cause a vehicle to fail emissions testing on a regular basis. A properly calculated and burnt air/fuel combination leaves no excess fuel or oxygen in the exhaust after it has been burned in the cylinders.
What causes a P0171 code and a P0174 code?
To begin, let us define what a P0171 code is. The official definition is P0171 System Is Too Lean (System is Too Lean) (Bank 1). When it occurs on a V-6 or V-8 engine, it is frequently accompanied by the P0174 System too Lean error code (Bank 2). Bank 1 of a ‘V’ engine is the bank that contains the cylinder number one. The P0171 and P0174 codes are the most often encountered issue codes across all automobile manufacturers. They are among the ‘Top Ten’ most frequently encountered fault codes that result in a vehicle failing emissions testing.
When there is too much oxygen in the exhaust, it shows that the air/fuel combination was not correct.
Vacuum leak that results in TOO MUCH AIR
A vehicle equipped with a MAF sensor detects all incoming air and notifies the driver of this fact. Because the MAF measures the volume and density of air entering the engine, any unmetered air that enters the engine will cause the computer’s air/fuel calculations to be incorrect.
Most common vacuum leaks are
Vacuum line is missing, damaged, or not connected in any manner. The air intake duct that leads from the MAF sensor to the compressor is damaged or torn. The air duct that connects the air filter box to the throttle body is also known as the throttle body duct The intake manifold gasket is leaking, and the fuel injector O-ring is leaking (the key to finding fuel injector O-ring leaks is to compare the fuel trims when cold versus hot because the o-rings tend to soften and seal better when hot).
The presence of exhaust leaks, which enable outside air to enter the exhaust and cause an overestimation of oxygen in the exhaust stream by the oxygen sensor.
Low manifold vacuum can cause a P0171 code and a P0174 code
Worn valves, valve seats, and worn piston rings are all examples of valve wear. It is possible for a cylinder to create less suction due to a vacuum leak in the manifold or carbon buildup on the valves. In order to determine the condition of your valve, use a manifold vacuum gauge. Troubleshooting sensor issues—If the MAF or MAP sensors aren’t operating properly, and the oxygen sensors are worn or polluted, the computer will make an incorrect air/fuel mixture calculation.
Most common sensor issues
Dirt or accumulation on the hot wire or plate of the MAF sensor, which acts as an insulator and causes the results to be inaccurate. MAF sensor that is not working properly The suction hose connecting the MAP sensor is either missing or broken. MAP sensor that is faulty or worn out, or an oxygen sensor that is polluted (s)
A P0171 code and P0174 code can also be caused by too little fuel
The readings from the sensors above are used by the computer to control the flow of gasoline. However, it is presumptively assumed that the gasoline delivery and metering systems are in proper operating condition. Neither the computer nor the engine can tell if the fuel pump is producing low fuel pressure or little amounts of gasoline or if the fuel injectors have become blocked. Gasoline injectors that are blocked or unclean are the most typical causes of too little fuel. High electrical resistance in the fuel power and ground circuits or relay, blocked fuel filter, a defective fuel pressure regulator, or a weak fuel pump can all cause low fuel pressure.
When there is a gasoline leak within a tank, fuel pressure and volume are lost between the pump motor and the in-tank pressure regulator, also known as a ‘pulsator.’
How to determine what’s causing the P0171 code and P0174 code
The most effective method of diagnosing and troubleshooting these error codes is to use a scan tool that shows live data. Take a look at the fuel trim information. Short and medium term fuel trims that are more than 10% indicate that the computer is adding fuel to compensate for either TOO MUCH AIR or too little fuel in the tank. If the fuel trims are negative, this means that the computer is removing fuel from the tank. If your engine is equipped with a MAF sensor, take note of the values from the sensor.
It is measured when the vehicle is at rest.
Don’t have a scan tool? Here are the things you can do to try and fix a P0171 code and P0174 code.
Make sure the MAF sensor is clean. Instructions may be found in this post. Vacuum leaks should be looked for. Check the vacuum hoses for cracks or tears, as well as cracks or tears in the air duct that runs from the air filter box to the throttle body. Spray carb cleaner around the O-rings of each fuel injector, as well as around the engine’s intake manifold gasket and head gasket, to observe if the cleaner is drawn into the engine by suction. Fuel pressure and volume should be checked. Alternatively, you may purchase or rent a fuel pressure test gauge from a local auto parts store.
If you are still unable to locate the root of the problem and do not have access to a scan tool, you may be able to solve the problem by throwing components at it.
Replace the MAF sensor with a new one. Replace the oxygen sensor if necessary. The year 2018 is a year of transition. Rick Muscoplat is a professional musician. Rick Muscoplat posted a blog entry on
P0171 and P0174 – System Too Lean
The items and services that we write about are chosen by our editors. If you make a purchase after clicking on one of our links, we may receive a commission. P0171 and P0174 are two codes that stand for ‘System Too Lean.’ But what exactly are the distinctions? What are the symptoms, what are the causes, and what can be done to fix them? All of this information is included inside one article.
- It often indicates that too much air is being drawn into your vehicle’s engine.
- As a result, it is critical to correct the code as soon as you see it.
- When the P0174 OBD2 code is shown, you know that the ratio is incorrect.
- Fortunately, you can diagnose and frequently correct the P0171 and P0174 error codes at your convenience.
- If you’re looking to learn more about the P0171 and P0174 OBD2 codes, you’ve come to the correct spot.
P0171 and P0174 Code Definition
The items and services that we write about are chosen by our editorial staff members. We may receive a commission if you make a purchase after clicking on one of our links. Get to know us a little better by visiting our website at System Too Lean is the meaning of P0171 and P0174, respectively.
- What are the signs and symptoms, what are the causes, and how do you treat them?
- It might be difficult to determine the root cause of the P0171 OBD2 error code.
- P0171 is a relatively benign error code, but it might cause subsequent harm that is more significant if left unchecked.
- Keep the proper mixture of air and fuel in your engine at all times in order to achieve top performance.
- A buildup of air in your system can increase your fuel consumption while also decreasing the power of your engine.
Fortunately, you can diagnose and frequently solve the P0171 and P0174 fault codes at your convenience at your own house. To find out what measures you should take, continue reading below. In this section you will learn all you need to know about the OBD2 codes P0171 and P0174.
P0174 Code Definition
P0174 Code (Generic): System is running at an excessively low level (Bank 2) P0174 Ford: The system is overly lean (Bank 2) P0174 To quote Toyota, ‘The system is too lean (A/F Lean, Bank2).’ P0174 B2P0174 – Nissan: Fuel System Lean B2P0174 ‘System is too lean (A/F Lean, Bank2),’ says BMW.
What Do P0171 and P0174 Mean?
The error number P0171 indicates that the air-to-fuel ratio in your engine is incorrect. For a combustion engine, the optimal compression ratio is 14.7:1. (14.7 parts air to each 1 part fuel). When the air-to-fuel ratio is greater than this, the combination is referred to as a ‘lean’ mixture. Engines that are more modern automatically correct for slight difficulties with the gear ratio. In the case of a lean mix, this implies injecting additional fuel to make up for the difference. Whenever the magnitude of these modifications becomes too great to be maintained sustainably, the issue code P0171 is triggered.
The P0174 fault code indicates that the air-to-fuel ratio in your vehicle’s engine is incorrect.
It differs from the comparable code P0171 in that it directs you to bank 2 of your system, rather than the other way around.
It is necessary for the powertrain control module to respond by injecting more fuel when the air/fuel ratio is greater.
What Are The Symptoms of The P0171 and P0714 Code?
The following are the most prevalent symptoms of a P0171 error code:
- The check engine light is illuminated
- It is difficult to start the engine
- The engine stalls after it has warmed up
- The engine stumbles or hesitates
- The engine runs rough
- Engine power has been reduced. Misfires and coughing from the engine
These signs and symptoms are also present in a range of other engine-related problems. Without the use of a diagnostic scanner, it might be difficult to determine if the engine is running on lean air to fuel.
Symptoms of P0174 Code
There will be some drivability concerns when the P0174 code is activated. The following are the symptoms of this error code:
- The check engine light is illuminated
- The vehicle is idling rough
- The engine is misfiring and coughing
- The vehicle’s power is reduced
- The vehicle surges when accelerating Fuel economy has been reduced.
What Are The Causes of P0171 and P0174?
In order for the P0171 code to be shown, the short-term fuel trim or the long-term fuel trim must both exceed a specific number, which indicates that the engine is modifying the air-to-fuel ratio more than it should. The process of determining the root cause of an error code begins with determining where the ratio is going wrong. The following are some of the most common underlying causes:
- The P0171 code is set when either the short-term fuel trim or the long-term fuel trim exceeds a predetermined value, indicating that the engine is altering the air-to-fuel ratio more than it ought to be. The process of determining the root cause of an error code begins with determining where the ratio is going incorrectly. The following are some of the most common root causes:
Causes of P0174 Code
There are several distinct systems that might cause the P0174 issue code to be displayed:
- Sensor for measuring mass airflow (MAF). A dirty or defective MAF sensor might cause the engine to believe that the mixture is too lean
- The oxygen sensor is another example. The oxygen sensor, like the MAF sensor, can malfunction, become filthy, or fail
- The PCV (positive crankcase ventilation) line is also susceptible to failure. P0174 is frequently caused by leaks in the PCV valve, as well as corrosion and cracks in the vacuum connection, among other things. Alternatively, the problem might be that the PCV line itself is broken or jammed open, resulting in vacuum leakage. P0174 is frequently caused by leaks in the pipes that run downstream of the MAF sensor. Cracks and damage in vacuum hoses, the PCV hose, or the intake manifold gasket, as well as a faulty fuel pump, can all cause this problem. Fuel injectors can get clogged as a result of a weak or defective fuel pump, which causes the fuel pressure to fluctuate, causing dirt to accumulate in the filters. The P0174 error code indicates that a fuel injector has failed. Clogged and filthy fuel injectors, as well as the exhaust system, might be the source of the problem. It’s possible that the exhaust system is leaking. It is also possible that a clog in the EGR (exhaust gas recirculation) port will have an impact on the air-to-fuel ratio
How Serious Is The P0171 and P0174 Code?
Airflow sensor known as a MAF (mass air flow). Incorrect readings from the MAF sensor, or a dirty or defective sensor, might cause the engine to believe the mixture is excessively rich; oxygen sensor. Oxygen sensor failure is similar to that of the MAF sensor in that it can malfunction, become filthy, or just stop working; PCV (positive crankcase ventilation) line P0174 is frequently caused by leaks in the PCV valve, as well as corrosion and cracks in the vacuum connection. In addition, it is possible that the PCV line is broken or jammed open, resulting in vacuum leakage.
Cracks and damage in vacuum hoses, the PCV hose, or the intake manifold gasket, as well as a faulty fuel pump, can all cause this problem to manifest.
The P0174 error code is caused by a faulty fuel injector.
Exhaust system problems can also be caused by clogged and filthy fuel injectors. There might be a leak in the exhaust system. It is also possible that a clog in the EGR (exhaust gas recirculation) port will have an impact on the air/fuel ratio.
How Do You Diagnose P0171 and P0174?
You’ll need the following tools:
- OBD2 scan tool
- Contact cleaner
- Fuel pressure gauge
- And anOBD2 scan tool
- Check your vehicle for any additional error numbers. If any additional issues arise, address them first before running the scan again. Assess the STFT (short term fuel trim) and the LTFT (long term fuel trim) statistics for your car to determine its fuel efficiency. When you perform this study, you will be able to see precisely how your system has been correcting for the air-to-fuel ratio and you will be able to pinpoint the source of the problem. Check for leaks in the vacuum lines and hoses of your engine’s intake manifold. When the engine is running, the most straightforward approach to detect a vacuum leak is to listen for a hissing sound. You may also inspect the tubes for fractures or rips, as well as hard or deformed regions, by feeling them. Any tubes that are damaged should be replaced. While you’re at it, double-check all of the connections to make sure they’re secure. Using a contact cleaner or brake cleaner, clean the MAF sensor once it has been removed. You should then delete the fault codes and re-scan your system after you have successfully installed the sensor. Step 4: Check for an exhaust leak by starting the engine and having an assistance idle the engine at 1,500rpm. If the P0174 error code is still present, go to step 5. If you hear any exhaust sounds coming from the manifolds or head pipes, turn off the engine. A leak can also be indicated by the presence of black smoke at certain locations. To check the fuel pressure in your system, you need use a fuel pressure gauge. Once you’ve obtained a reading, consult your vehicle’s specs to see what the recommended fuel pressure is. Examine the filter or line to see if it has become clogged if the reading is too low. If you have a multimeter, you may use it to check the voltage of the pump to ensure that it is still operating properly.
If none of the above techniques reveal the source of the problem, the oxygen sensor should be checked using a multimeter. Visually check it for grime and clean it with contact cleaner before reinstalling and scanning it once more for errors.
How to Diagnose P0171?
The systems that might cause this issue code to be triggered are many, as you can see in the list above. The good news is that you can discover the specific cause of the problem by following a few straightforward procedures.
- Check for any other error codes. If you locate any, take care of them first. With the use of a vacuum gauge, check the engine for leaks in the vacuum system. Make sure to do this with the motor switched off so you can hear the air escaping through any leaks that are present. Repair all of the sources of vacuum leaks, reconnect all of the components, and clear any trouble codes that may have appeared. Re-scan your system to make sure everything is working properly. If the issue code continues to appear, go to step 4: remove the mass airflow sensor and clean it with a contact cleaner before replacing it. Reinstall it, clear the codes, and run a system scan on your computer. Then go to step 5 if the code is still shown. Check your fuel filter and fuel pump to make sure they are in good working order. Remove and clean them, then replace all of the components and use a fuel pressure gauge to test the fuel pressure sensor and the mass airflow sensor, if necessary. Start your engine and let it warm up to operating temperature before continuing. Check the reading from the mass airflow sensor, which indicates the barometric pressure. if it’s reading about 26 Hg, it’s probable that the mass airflow sensor isn’t working properly and is under-reporting the air density
- If no problems are discovered with the tests listed above, you should check your oxygen sensors. They will very certainly need to be replaced
What Common Mistakes Should You Avoid While Diagnosing Code P0171 and P0174?
It is the most common mistake that individuals make that they do not follow through with the whole diagnostic. The air-fuel sensor may need to be replaced later on if the underlying problem is found to be farther down the line. The P0171 code is also frequently misinterpreted as indicating a problem with the oxygen sensor. Always pay close attention while replacing a component to ensure that you are replacing the correct component. The most common mistake individuals make while diagnosing P0174 is failing to complete the whole test.
If the problem is caused by a blockage or a malfunction elsewhere in the system, this will not address it.
What Should You Do to Fix P0171 and P0174 Codes?
OBD2 scanners can assist you in identifying the p0171 error code.
How to fix P0171?
As stated in step 3 of the diagnosis above, begin by correcting any vacuum leaks that may have occurred. Not only is this a common source of problems with the air-to-fuel ratio, but it’s also the cheapest and simplest solution to resolve the problem as well. If the vacuum seals are in good condition but the error continues to appear, perform the following steps: 1.
- Using brake cleaner or electronics cleaner, remove the mass airflow sensor and thoroughly clean it. Before reinstalling it, be certain that it is entirely dry. Make that the gasoline filter is in good working order. In case it’s unclean or isn’t maintaining sufficient fuel pressure, it should be replaced. To determine how much the powertrain control module is altering the air/fuel mixer, use an advanced scan tool to examine the short-term fuel trim and the long-term fuel trim. Use this information to determine if you need to replace the fuel pressure regulator, fuel pump, fuel injectors (if applicable), oxygen sensor, or the whole powertrain control module.
How to Fix P0174?
Cleaning the MAF filter and correcting vacuum leaks are two common ways to resolve the P0174 error number. If they don’t, you’ll most likely need to replace one or more of the components, which you may accomplish by following the procedures below:
- Repair any leaks that have been discovered in the exhaust system, as well as any filthy filters or blocked lines that have been discovered
- Again, make sure your system’s fuel pressure is within acceptable limits. Check and replace the fuel pump and fuel injectors if the level is still too low. Check both the oxygen sensor and the MAF sensor for proper operation. If they’re soiled or damaged, you should replace them. Check the PCV valve and the EGR valve, and replace them if necessary.
Utilize an OBD2 scanner to clear the codes after completing each step, and then verify your system to determine whether the problem has been repaired.
Tips To Avoid P0171 and P0174 In The Future
Preventing excessive air from entering your engine can assist you in maintaining the proper air to fuel ratio over the long run. Checking for leaks in the vacuum lines and gaskets is a simple and straightforward process:
- Open the hood and visually examine all of the lines for cracks and other damage before continuing. These are most typically located at the end of a line
- Start your engine to find out where they are. Spray carburetor cleaner around the gaskets of your automobile while it is running at idle. If the engine speed rises, you have a leak
- Otherwise, you don’t.
An exhaust leak might potentially allow air to enter your fuel system, resulting in a P0171 code being displayed on your dashboard. To check for an exhaust leak, do the following:
- Start your automobile and instruct your assistance to idle at around 1500rpm
- Keep your ear close to the engine and listen. In the event that you hear exhaust noises originating from the head pipes or manifolds, you most likely have a leak. Inspect the system for any signs of black soot escaping from any part of it, which is another strong evidence of an exhaust leak.
How to Avoid P0174?
The accumulation of dirt on over-oiled engine components, such as the MAF sensor, can cause them to become stuck and cause damage or clog the system. Check and clean your engine on a regular basis to avoid blockages and debris build-up, which are typical sources of damage to lines and other components of your vehicle. If you need to repair components, try to figure out why they failed first before replacing them. The oxygen sensors, for example, are frequently destroyed as a result of coolant leaks.
It is possible that your new sensors will fail just like your previous ones did if you do not discover and rectify the source of the leak. More information may be found at: P0172 Code Definition, Symptoms, Causes, Diagnosis, and Repair Information
P0171 and P0174 Codes – Don’t change an Oxygen Sensor Before Reading This
You’ve noticed that your car’s CEL (always check engine light) is on, and you’ve also had the codes read at a nearby parts store. (Alternatively, you may use your ownOBD scanner to retrieve the automobile defects.) Your automobile or truck has either a P0171 or a P0174 lean error code saved in the computer, or both. These codes are derived from readings from the Oxygen Sensor (O-2) in the engine. A lean code or a series of lean codes indicate that there is definitely too much air in the exhaust.
- These codes are derived from the dimensions of the air in the exhaust system.
- This might turn out to be a very costly mistake that does little to alleviate the situation.
- Vacuum pressure leakage is most likely the primary reason.
- Keep an ear out for a hissing sound that might point you in the direction of the source of the problem.
- With today’s computers, it is not nearly as simple to check for vacuum cleaner leaks in this manner since the ECU (Electronic Control product) will rapidly compensate for the included gas and a change in idle is more difficult to detect.
- Professionals may also use a smoke test to detect vacuum cleaner leakage, which is another method of detection.
- Aftermarket air filters that employ oil on factor might cause the MAF to malfunction on occasion.
This may cause the reading to be altered, deceiving the ECU into believing that just a little amount of air is flowing, causing the air/fuel blend to be incorrectly adjusted.
In the MAF, there was a burned piece of garbage that led it to be’s method at night air conditioner filter, which was discovered when inspecting the cable.
The ash that had accumulated on the MAF sensor wire ended up affecting the reading by enriching the mixture to the point that the automobile was unable to drive.
This was plainly caused by some debris getting into the air intake pipe, which resulted in the MAF being turned on by the hot wire.
If the gas filter is clogged or if the gas pump pressure is enough, there may be a greater concentration of oxygen in the exhaust as well.
As a result, this is one of the least probable aspects that contribute to a lean program.
If you get a P0171 or P0174 code, don’t update your oxygen sensor until you’ve read this.4.1 (82.86 percent ) 21votes
Ford P0171 & P0174 Lean Codes
Automobile Repair Library, Auto Parts, Accessories, Tools, Manuals and Books, Car BLOG, Links, and more. Index byLarry Carley (c)2019 AA1Car.com All rights reserved. A Ford P0171 LEAN code corresponds to cylinder bank 1, whereas a Ford P0174 LEAN code corresponds to cylinder bank 2. On many Ford cars, these codes are often encountered, and they are set when the powertrain control module (PCM) determines that the air/fuel mixture is running too lean (too much air, not enough fuel). It is possible to find any one of these codes, or both of these codes, when a code reader or scan tool is inserted into the vehicle’s diagnostic port and the Check Engine Light illuminates.
On Ford cars equipped with a V6 or V8 engine with rear-wheel drive, the cylinder bank on the RIGHT (passenger) side of the engine is designated by the P0171 lean code for bank 1.
On four-cylinder engines, this code is not activated (no bank 2).
WHAT A LEAN CODE MEANS
It is possible to have a lean fuel condition when the engine is taking in too much air and/or when the fuel system is not supplying enough fuel. Depending on the severity of the situation, a low fuel condition may result in lean misfires, a rough idle, reluctance or stumble when accelerating, and/or poor overall engine performance. Vacuum leaks, a filthy airflow sensor that is not measuring airflow properly, an EGR valve that is not closing and enabling exhaust to leak into the intake manifold, and an EGR valve that is allowing too much flow are all examples of how unmetered air might enter the engine (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).
A clogged MAF sensor might cause a lean code to be generated.
COMMON CAUSE: A DIRTY MAF SENSOR
P0171 and P0174 lean code problems are frequently caused by a filthy mass airflow (MAF) sensor, which is one of the most typical reasons. The MAF sensor is positioned in the air inlet tube, immediately ahead of the throttle body, and it is responsible for measuring air flow. The air filter is supposed to shield the MAF sensor from dust and debris from the outside world, however sometimes the air filter does not fit tightly enough inside the housing, allowing unfiltered air to get through to the engine.
- Additionally, gasoline vapors that accumulate in the intake manifold and throttle body after the engine has been turned off might contaminate the mass air flow sensor (MAF).
- This leads to an underreporting of airflow by the mass airflow sensor (MAF), which in turn causes the powertrain control module (PCM) not to supply enough fuel in order to maintain a correctly balanced air-fuel ratio.
- One method of diagnosing a clogged MAF sensor is to connect a scan tool to the vehicle, choose the PID data option, and examine the fuel trim values while the vehicle is operating.
- If the MAF sensor is clogged, the solution is straightforward: just clean or replace the sensor.
- Any other form of cleanser should not be used since it may cause harm to the sensor.
- Allow the cleaner to soak in for a few minutes before spraying it with another shot of cleaner.
Allow it to rest for another five minutes before reconnecting the air inlet tube and turning on the ignition. It is possible that the MAF sensor will need to be changed if the lean codes keep appearing despite the fact that the engine is not suffering from a vacuum leak or fuel delivery problem.
ANOTHER COMMON CAUSE: VACUUM LEAKS
A vacuum leak in the engine is another typical cause of Ford P0171 and P0174 lean code problems. Vacuum leaks can occur anywhere in the intake pipework that is downstream of the throttle body, including the throttle body itself (throttle body gasket, intake manifold gaskets or vacuum hose connections to the intake manifold) A vacuum leak can be diagnosed with the use of a scan instrument. Connect your tool, start the engine, then choose the PID data menu from the drop-down menu. Take a look at the fuel trim numbers when the engine is running at idle.
- Increase the engine speed to 2500 RPM.
- Ford Technical Service Bulletin 04-17-4 describes the steps to be followed while testing for fuel trim and vacuum leaks.
- This is commonly caused by oil being sucked into the engine through the PCV system.
- According to Ford Technical Service Bulletin 03-16-1, the remedy consists of multiple steps: It is necessary to remove the upper manifold plenum and replace it with a revised one that has less oil vapor drawn into the PCV system.
- Finally, it is necessary to reflash the PCM to make it less sensitive to lean fuel conditions.
ANOTHER POSSIBILITY: LOW FUEL VOLUME DELIVERY
It is also possible to establish lean codes if the engine is not receiving enough gasoline. If you have a weak fuel pump, low voltage to the fuel pump (which stops the fuel pump from spinning quickly enough to produce regular fuel flow), a blocked fuel filter, or a leaky fuel pressure regulator, these might all be contributing factors. Diagnose Fuel Pumpfor additional information on how to solve fuel delivery issues. Diagnose Fuel Pump You may also use a diagnostic program to examine fuel supply issues that may be causing a lean code to appear on your computer screen.
- If the fuel pressure is less than the standards, it is likely that there is a problem with the fuel pump or the fuel pump wiring circuit.
- At idle, the fuel trim may be normal to somewhat positive, depending on the engine.
- It would be reasonable to conclude that there has been no change in fuel trim values and that low fuel volume is not the source of your lean code.
- It is possible that they flow enough fuel at idle and low speed to keep up with engine demand, but that they do not spray enough fuel at higher engine speeds and loads in order to maintain the correct air/fuel ratio.
Cleaning the fuel injectors is the solution for unclean fuel injectors. If the injectors are really unclean, fuel tank additives may be inefficient or even useless, and it may be required to have the injectors professionally cleaned.
IT COULD ALSO BE: A BAD DPFE SENSOR
It is also possible for a defective EGR differential pressure sensor to cause Ford p0171 and p0174 lean faults. Once a vehicle has accumulated more than 60,000 miles on the odometer, or if it is more than five or six years old, the failure rate of these sensors becomes quite high. In addition to being installed on the engine, the DPFE sensor is connected to the tube that conducts exhaust gas to the EGR valve by means of two rubber hoses. The sensor’s original equipment enclosure is made of rectangular aluminum and is approximately three inches in length.
It responds by boosting EGR flow, which may cause the EGR valve to remain open for a longer period of time than typical, resulting in a too lean state in the engine.
The most common cause of the P0401 error is a faulty DPFE sensor, rather than a malfunctioning EGR valve or an EGR valve that has been clogged with carbon (though this can also set a P0401 code).
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It is also possible for a bad EGR differential pressure sensor to cause Ford p0171 AND p0174 lean codes. When a vehicle has more than 60,000 miles on the odometer or is more than five or six years old, the failure rate of these sensors is quite high. In addition to being installed on the engine, the DPFE sensor is connected to the tube that conducts exhaust gas to the EGR valve by means of two rubber hoses, as shown in the illustration. With a rectangular aluminum housing of approximately three inches in length, the original equipment sensor is easy to recognize.
It responds by boosting EGR flow, which may cause the EGR valve to remain open for a longer period of time than typical, causing the engine to run lean.
A malfunctioning DPFE sensor, rather than an EGR valve issue or an EGR valve clogged with carbon, is the most common cause of the P0401 code in the majority of situations (though this can also set a P0401 code).
P0171 – Meaning, Causes, Symptoms, & Fixes
Bank 1 either contains an excessive amount of air or an insufficient amount of fuel.
What Does P0171 Mean?
Combustion engines operate most efficiently when the air-to-fuel mixture ratio is maintained at 14.7 parts air to one part fuel. There is a lean state present when there is more than 14.7 parts air to 1 part fuel in the air-fuel combination, and the code P0171 is activated. In addition to vacuum leaks, which bring more air into the air-fuel mixture, a weak fuel system, which does not inject enough fuel into the air-fuel combination, can result in a lean situation as a result of a weak fuel system.
When the magnitude of these modifications exceeds a certain threshold, code P0171 is triggered.
What Are The Symptoms Of P0171?
- Check Engine The engine is not producing enough power
- The engine is making a rough idle
- The engine is coughing
- The engine is misfiring.
What Is The Cause Of P0171?
- Clean or malfunctioning mass airflow sensor
- PCV hoses, vacuum hoses, and the intake manifold gasket all have vacuum leaks. Fuel pump that is not working properly
- Fuel injectors that are clogged or filthy
- Fuel filter that has become clogged
- Leak in the exhaust system
- Faulty oxygen sensor
- Faulty air-fuel ratio sensor
- Faulty oxygen sensor
How Serious Is Code P0171? – Moderate
Driving a vehicle with the P0171 code for a short amount of time is OK; however, driving a vehicle with this code for a longer period of time might cause the engine to overheat and cause internal engine damage.
Code P0171 Common Diagnosis Mistakes
When diagnosing P0171, it is critical that the full diagnostic process be completed in its entirety. Despite the fact that many individuals immediately replace the air-fuel sensor or oxygen sensor when they receive a wrong reading, the fundamental reason is frequently a filthy or malfunctioning mass airflow sensor or vacuum leak, which causes the O2 or A/F sensor to read differently in order to adjust for the problem. The ability to read and analyze gasoline trims as well as freeze frame data is essential for correctly diagnosing P0171.
Tools Needed To Diagnosis P0171
- You Might Require the Following Tools: (FIXD’s top-recommended Amazon selections are as follows:
- In addition to FIXD ($59.99), Mass Air Flow Cleaner ($11.31), Fuel Pressure Testing Gauge ($25.99), and Hayne’s Repair Manual ($19-$25), there are several more items to consider.
How To Diagnosis Code P0171
Diagnose and repair are difficult — 3 out of 5 on the difficulty scale.
- P0171 is the only code that should be present, therefore scan your car using FIXD to confirm. If there are any additional codes present, they must be dealt with first. Check for leaks in any vacuum lines and hoses, and double-check that they are all securely linked together. While driving, you will hear a hissing sound that indicates the presence of a leak. However, it may be difficult to detect while the engine is running. Look out this comprehensive guide to discovering and correcting vacuum leaks if you believe you have one but are having difficulty locating it
- After reconnecting any disconnected vacuum lines and replacing any broken vacuum lines that are leaking, use FIXD to delete the check engine light code P0171 from the vehicle’s computer. Once again, if the check engine light (code P0171) illuminates, check for leaks in the remaining vacuum lines before continuing with the rest of the diagnostic procedure. Remove the mass airflow sensor and clean it with a mass airflow cleaner or a contact cleaner before reinstalling it. Using FIXD, reinstall the mass airflow sensor and reset the check engine light on the vehicle. The diagnostic process should be repeated if the check engine light comes back on and displays code P0171. If you have determined that there are no vacuum leaks, that your mass airflow sensor is clean, and that your fuel system is operating correctly, check the exhaust for leaks before checking the Air Fuel Ratio Sensors or the Oxygen Sensors
- If you discover any leaks, get them fixed. You may want to investigate changing your A/F sensor or O2 sensors at this stage if the code still persists beyond this point.
Estimated Cost of Repair
If you receive error code P0171, one or more of the fixes listed below may be required to resolve the underlying problem. The estimated cost of repair for each feasible repair includes the cost of the essential components as well as the cost of the labor required to complete the repair, if any.
- Clean the MAF for $100
- Replace the MAF for $300
- Fuel Pump $1300-$1700
- Fuel pressure regulator $200-$400
- Exhaust repair $100-$200 (if welded to repair)
- Air fuel sensor or oxygen sensor $200-$300
- Exhaust repair $100-$200 (if welded to repair).
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P0171 Diagnostic Trouble Code – What You Need to Know
Because the engine is running low on bank 1, the air to fuel ratio is heavily skewed in favor of the air.
What P0171 really means
The computer can make corrections over time as the engine ages, components fail or measurement sensors become defective. The computer may do this by increasing the amount of time the fuel injectors are turned on in order to richen the mixture. This code can also be used in conjunction with a P0174, which will indicate that bank 2 is lean. To achieve optimal combustion efficiency, the ideal stoichiometric ratio is 14.7 parts air to 1 part fuel. This provides for an excellent combination of fuel economy, performance, and fewer emissions during combustion.
What are the symptoms for a P0171 code?
It is common for lean codes to cause the engine to run badly, which the driver would notice as a high idle, a misfire, a loss of power, or even engine stalling. This can occur even before the check engine light illuminates. Furthermore, these symptoms will be more obvious at slower speeds and lower RPMs than at higher speeds and RPMs. The engine is better able to deal with lean conditions at higher speeds since the demand for air is larger.
What is the severity of a P0171 code?
Critical. A diagnostic check should be performed as soon as possible to determine the specific nature of the problem.
What repairs are required for a P0171 code?
There is a broad list of reasons why the engine runs lean, and a qualified technician will require time to figure out what is causing the issue. The problem, in contrast to rich difficulties, can occur on either side of the mixture – either too much air or not enough fuel. To be sure, there are some straightforward solutions – a broken vacuum line will allow air into the vehicle that the computer cannot account for, and a blocked fuel filter would reduce the amount of fuel that can be delivered.
Prepare for the possibility of dropping off the car and allowing enough time for the technician to figure out what’s wrong.
What is the cost to resolve a P0171 code?
- It is estimated that the diagnostic cost will be $100
- That the part(s) and labor costs will be $50–$800 (depending on the diagnosis)
- And that the overall cost will be $150–900.
This code will necessitate a diagnostic check, which will cost around $100 depending on how long it takes to identify the problem. In light of the fact that there is a laundry list of reasons why the engine runs thin, the average cost of each repair will vary significantly. Perhaps one of the easy fixes listed above will turn out to be a fortuitous break. A damaged vacuum hose sucking in air can cost as little as $50, while a blocked fuel filter might cost as much as $100. An oxygen sensor or a mass air flow sensor, on the other hand, can result in a cost of $400 to $500 dollars.
If your car is displaying this code, you should arrange a diagnostic check with a professional as soon as possible.
It’s not an issue.
Written by an ASE Master Technician, this service article provides information on Obtain price quotes from neighboring businesses.