P0138 Hyundai?

  • The P0138 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time. | What are P0138 HYUNDAI code possible symptoms? Engine Light ON (or Service Engine Soon Warning Light) High Fuel Consumption Excessive Smoke from Exhaust

How do I fix error code P0138?

What repairs can fix the P0138 code?

  1. Replacing the O2 sensor for bank 1 sensor 2.
  2. Repairing or replacing the wiring or connection to the O2 sensor for bank 1 sensor 2.
  3. Replacing the catalyst in front of the sensor.
  4. Repairing a leaking injector.

What causes code P0138?

When trouble code P0138 is set, this indicates that there is a high voltage (steadily above. 9 volts) for more than 10 seconds indicating a lack of oxygen in the exhaust stream and an abundance of fuel at sensor 2 on the bank 1 of the engine.

Where is oxygen sensor in Hyundai Accent?

The Hyundai Accent oxygen sensor is located on the exhaust before and after the catalytic converter.

How do you fix a high voltage O2 sensor?

The number one most common repair for this problem is replacing the O2 Sensor itself. Another repair would be to replace the wiring or connection for Bank 1, Sensor 2. If the catalyst is the problem, replace the catalytic converter. Replace the fuel injector if it is leaking.

Where is oxygen sensor located?

The sensor is typically located on the passenger side of the car, mounted directly onto the exhaust pipe near the catalytic converter. When the sensor goes bad, your car may lose up to 40 percent of its fuel efficiency, because your car will use too much gas.

How much does it cost to fix O2 sensors?

A brand new replacement oxygen sensor can cost you from $20 to $100, depending on the make and year of your car. Taking your car to a mechanic to fix the issue can cost up to $200.

What are the symptoms of a bad oxygen sensor?

Here are some of the most common signs that your oxygen sensor is bad.

  • A Glowing Check Engine Light. The bright orange Check Engine light in your dashboard will usually glow if you have a bad oxygen sensor.
  • Bad Gas Mileage.
  • An Engine That Sounds Rough.
  • An Emissions Test Failure.
  • An Older Vehicle.

What is code P0141 mean?

Code P0141 occurs when the powertrain control module tests the downstream heated oxygen sensor’s heater circuit on Bank 1 and detects a short in the circuit or excessive resistance in the heater circuit.

Will a oxygen sensor stop a car from running?

This is done through the oxygen (O2) sensor. Driving with a faulty O2 sensor means the computer won’t be getting the correct reading of the mixture and hence it won’t be able to adjust the air-fuel mixture properly. But if your engine starts and runs, and can stay running, it’s drivable.

Is Bank 1 Sensor 1 Left or right?

Bank 1 Sensor 1 is located right before the catalytic converter.

Is Bank 1 upstream or downstream?

Bank 1 Sensor 1 means Upstream Right/Rear;Bank 2 Sensor 1 means Upstream Left/Front;Bank 1 Sensor 2 means Downstream Right/Rear;Bank 2 Sensor 2 means Downstream Left/Front.

How do you reset the check engine light after changing O2 sensor?

Turn the ignition to the “On” position but don’t crank the engine (it won’t start anyway). Wait five minutes and reinsert the fuse. The “Check Engine” light will blink, then shut off.

Is P0138 code upstream or downstream?

P0138 is definitely downstream. On OBDII, the upstream is the primary input for determining fuel/air ratio, but I did read a technical paper from Chrysler where they stated that some (minimal) feedback input from the downstream is involved as well. Regardless, start with replacing the downstream for a P0138.

Which 02 sensor is bank 1 sensor 2?

Air Fuel Ratio/Oxygen Sensor Identification A typical in-line 4-cylinder engine has only one bank (Bank 1). Therefore, in an in-line 4-cylinder engine, the term “Bank 1, Sensor 1” simply refers to the front oxygen sensor. “Bank 1, Sensor 2” is the rear oxygen sensor.

What voltage should a O2 sensor read?

An O2 sensor will cycle between 0.10 to 0.90 or almost 1 volt. An O2 sensor has to reach the 0.8x Volts amplitude mark while at full operation. An O2 sensor also has to reach the 0.1x Volts amplitude mark while at full operation.

P0138 – Meaning, Causes, Symptoms, & Fixes

High Voltage O2 Sensor Circuit Design (Bank 1, Sensor 2)

What Does P0138 Mean?

Oxygen sensor 2 is the oxygen sensor that is downstream of the catalytic converter in terms of position. It monitors the amount of air and fuel that is expelled from the catalytic converter in order to confirm that the catalytic converter is operating correctly. If the voltage is high (approximately.9V), this indicates that there is an excess of fuel in the mix. If the voltage is low (about 1V), this indicates that there is too much air in the mixture. This means that a continuous 0.45 volts should be produced by the downstream oxygen sensor (sensor 2) in order to ensure proper operation.

What Are the Symptoms of Code P0138?

  • Check Engine Light on
  • Engine overheats
  • Worse fuel economy
  • Rough idle
  • Strong fumes
  • Check Engine Light on

What Is the Cause of Code P0138?

  • O2 sensor that is not working properly
  • A short to battery voltage in the O2 sensor signal circuit
  • Fuel pressure is too high due to corroded wiring. Sensor for the temperature of the engine coolant

How Serious Is Code P0138? – Moderate

Driving a car with the P0138 code for a short amount of time is OK, however driving a vehicle with this code for a longer period of time might cause damage to the catalytic converter (s).

Code P0138 Common Diagnosis Mistakes

Replacing the oxygen sensor without first determining if the car is running rich as a result of another problem is a mistake.

Tools Needed to Diagnose Code P0138:

Difficulty in Diagnosing and Repairing the Problem – (2 out of 5)

  1. Check for damage to the wire at the O2 sensor
  2. If there is damage, repair or replace the affected harness. It is necessary to check the voltage at the oxygen sensor
  3. If the voltage is consistently high (.9V or above), the oxygen sensor may be defective. Before replacing, make sure that the following items are in working order:
  1. Check to ensure that the coolant temperature gauge is functioning correctly (see the vehicle handbook for specifications)
  2. Check to verify that the fuel pressure is within specifications.
  1. It is recommended that you replace the downstream O2 sensor in bank 1 if the O2 sensor is reading high voltage and the fuel pressure and coolant temperature are within specifications.

Estimated Cost of Repair

If you receive error code P0138, 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.

  • Fuel pressure regulator $200-$400
  • Engine coolant temperature sensor $150-$200
  • Oxygen sensor $200-$300

Hyundai Sonata P0138: Oxygen Sensor High Voltage (Bank 1 -Sensor 2)

The code P0138 is a commonly seen OBDII error that may be found in a variety of automobiles, including the Hyundai Sonata. When the following conditions are met, the code is activated:

  • For at least 20 seconds, the voltage at the sensor remains over the threshold value. The voltage applied to the sensor is too high (a fault with the wiring, imagine short)
  • The O2 sensor itself is faulty
See also:  GM engine leaks and DexCool?

In certain cases, for up to 20 seconds or more, the voltage at the sensor remains over threshold. Insufficient voltage applied to the sensor (wiring issue, maybe short); A faulty oxygen sensor;

Hyundai Sonata P0138 Symptoms

Typically, the sole symptom of P0138 is the presence of the service engine soon indicator light on the dashboard. In certain circumstances, there may be additional signs and symptoms as well. These are some of the signs and symptoms:

  • Engine has a rough idle
  • The exhaust smells
  • The service light is illuminated
  • The MPG is poor.

The majority of the time, there is no danger of a breakdown. However, like with anything that causes the service engine soon light to illuminate, it is a good idea to get it repaired as soon as it is discovered. An insufficient air-to-fuel combination passes through the catalytic converter.

Hyundai Sonata P0138 Causes

The following are the most often seen problems that result in the P0138 code in the Hyundai Sonata. They are provided in a sort of descending sequence from most to least likely to be the source of the problem.

  • Bad Oxygen Sensor – The O2 sensor itself is one of the most common causes of the P0138 code prompting your service engine soon warning light to illuminate. Although it may be tempting to replace it straight immediately, it would behoove you to first inspect the wire harness that surrounds it. See the section just below. They are reasonably priced at places like Autozone or Amazon. Problems with Wiring Harnesses – The cable that connects the front and rear oxygen sensors is extremely prone to failure due to corrosion. Due to the fact that O2 sensors are located under the chassis, they are prone to damage from road debris as well as a great deal of exhaust heat, this is the case. In particular, the downstream sensor is vulnerable to this phenomenon. On YouTube, you may learn how to locate a short in a wire harness. Deterioration of the Terminal – The terminal (the socket) to which the oxygen sensor is connected is likewise a rather vulnerable component to damage. You’ll want to double-check that there’s electricity flowing to the device. More information about this may be found straight below
  • Incorrect O2 Sensor – The P0138 code may be shown after you have recently changed your Oxygen sensor. It is possible that the replacement was incorrect or defective.

Sonata P0138 Diagnosis

With the aid of a multimeter, it is easy to diagnose the P0138. If you use the multimeter, you’ll be able to see whether or not the voltage coming to and from the oxygen sensor is within specification. This can assist you in determining if the problem is with your Sonata’s oxygen sensor or wiring harness. Unless you happen to be in possession of a multimeter, it would behoove you to examine the wire that connects to the fuse box and the oxygen sensor first. If it turns out to be a wiring problem, you’ll save money by not having to purchase an unneeded O2 sensor.

If there is no electricity coming from the harness plug, attach the test light to the plug and jiggle the wiring a little bit. Whenever the light illuminates, even for a fraction of a second, you know that you have a short circuit, which is causing the P0138 issue code to appear.


Good luck in identifying the source of the P0138 code on your Hyundai Sonata. If you have anything to contribute, please feel free to do so in the comments section below this post.

OBD-II Trouble Code: P0138 Oxygen Sensor Circuit High Voltage (Bank1, Sensor2)

High Voltage Oxygen Sensor Circuit O2 Oxygen Sensor Circuit (Bank1, Sensor2)

What does that mean?

This diagnostic trouble code (DTC) is a general powertrain code, which means that it applies to any cars that are equipped with the OBD-II diagnostic system. Despite the fact that they are general, the particular repair processes may differ based on the make and model. The Heated Oxygen Sensor (2), which is placed at the back of the catalytic converter, gives an output signal that is proportional to the ability of the catalytic converter to store oxygen. Bank 1 refers to the side of the engine that holds the first cylinder of the engine.

HO2 Sensor voltage must be more than 999 mV for more than 2 minutes (duration varies depending on model) before this code is activated.


With the exception of MIL lighting, there may be no apparent symptoms. A possible increase in fuel pressure may cause the system to become too rich.


One or more of the following events may have occurred, resulting in the code P0138:

  • A faulty oxygen sensor
  • A short between the battery voltage and the signal circuit for the oxygen sensor
  • High fuel pressure (although this is less common)

Possible Solutions

Here are some suggestions for potential solutions:

  • Replace the oxygen sensor
  • Repair a short in the battery voltage in the o2 sensor signal circuit
  • And replace the O2 sensor.

Related DTC Discussions

  • P0132 AND P0138 for the 2000 Caravan So. I was unable to pass DEQ since my status was marked as Not Ready. I agreed with the repair shop’s recommendation to replace the PCM. As a result, I purchased a PCM that had been VIN encoded online. Installed. And now I have both P0132 and P0138 on my computer. So, it appears that the oxygen sensors are malfunctioning. Replaced. It’s the same problem. In addition to rich burning, stuttering, and lagging
  • P0138 is the model number for the 2005 Toyota Prius. I’ve been pulling my hair out over this issue for quite some time. I’ve changed the oxygen sensor on my car twice (getting one bad one is not too rare). My computer is equipped with TechStream software, which allows me to view test results for catalytic converter performance and make adjustments such as adjusting the fuel injection ratio. The vehicle has 21 license plates: 99 Dodge Caravan – P0132, P0138, and P0172. With roughly 80K miles on my 1999 Dodge Caravan Sport van, with a 3.3-liter engine, I’m having trouble getting rid of the O2 codes. There is no doubt that the engine is running rich. It has a foul odor. Initially, when it is restarted hot, it idles quite rich (rough) for around 2 minutes before suddenly revving up by itself and running smoothly idle. Occaisio
  • s2003 Kia Rio 1.6L P0447, P0038, P0138, P0170, P0501, P0447, P0038, P0138, P0170, P0501 The P0447 code is one of numerous that my car has, and it is described as EVAP emission system – vent control valve circuit open on the manufacturer’s website. I have no idea where to begin looking because I am unsure whether or not this vehicle has a sensor in the gasoline tank. I am aware that it is necessary to have an external carbon canister near the tank. Do you have any suggestions? P0138 is the code to use. I’m new to the Dodge Ram 1500 P/UI’m new to the site. After going through numerous issue code discussion sites, it appears that this crew is on top of things. Please bear with me since I am not a professional technician. The car is a 1999 Dodge P/U with a 3.9-liter V-6 and 126,000 miles, which I acquired new in 1999 from Dodge. The majority of the upkeep is completed by myself. Recent repair performed
  • P0138 on a 2000 Jeep TJI recently had the codes examined and discovered P0138, which I cleared, but it reappeared after a short drive
  • The car runs well, but I notice it is running rich while backing into the garage
  • Any suggestions as to what can be causing this? Rob
  • s98 Dakota P0138 code description I have a 1998 Dakota 4×4 (3.9 5 speed) and the check engine light came on, and I scanned the code and found P0138. I changed both sensors and restarted the computer to no avail. The light turned on again about ten miles down the road with the same code as the first time. It took me 97 minutes to trace every wire I could find, seeking for any symptoms of danger
  • Vehicles with the codes p0340 p0118 p0108 p0351 p0113 p0138, as well as stalling Welcome to the forum, I’m a first-time poster with a 1997 Grand Cherokee Laredo 4.0L. ACTRON scan tools were used to read all of the codes. There will be no remote start or alarm after the market. P0340 tps high voltage (P0340 tps) P0118 high voltage engine coolant sensor (P0118) P0108 is a high voltage map. Primary circuit for the P0351 coil (no idea what that means.) P0113 IAT high voltage
  • P0123/P0351/P0138 P0123/P0351/P0138 Recently, I’ve been experiencing some difficulties with my truck. The issues I’ve encountered are a harsh idle that eventually causes the car to die, as well as hesitancy when starting off from a stop. Additionally, the torque converter will not lock up. The vehicle has more than 150,000 kilometers on it. I have performed the routine maintenance on the transmission every 50,0
  • I have also repaired the P0132 and P0138 codes on my 2004 Chrysler Pacifica2004 Chrysler Pacifica AWD, Automatic 3.5L, 79K miles. Repairs completed recently include: Catalytic converter aftermarket vs. original equipment manufacturer The cat has been plugged, resulting in power loss. 2 new O2 Sensors – The tips of the old O2 sensors were coated with a white powder-like material. New PCM – initial diagnostic by a technician (the check engine light came back on after the doctor
See also:  AC compressor clutch won’t engage – Toyota?

Need more help with a p0138 code?

If you still need assistance with the P0138 error code, please ask your issue in one of our FREE vehicle repair discussion boards. Please keep in mind that this material is being provided solely for informational reasons. It is not meant to be used as repair advice, and we are not liable for any actions you take in relation to any vehicle. All of the information on this website is protected by intellectual property rights.

Solution OBD Error Code P0138

P0138 Acura OBD Error Code P0138 Honda OBD Error Code P0138 Mitsubishi OBD Error Code
P0138 Audi OBD Error Code P0138 Hyundai OBD Error Code P0138 Nissan OBD Error Code
P0138 BMW OBD Error Code P0138 Infiniti OBD Error Code P0138 Porsche OBD Error Code
P0138 Buick OBD Error Code P0138 Jaguar OBD Error Code P0138 Saab OBD Error Code
P0138 Cadillac OBD Error Code P0138 Jeep OBD Error Code P0138 Scion OBD Error Code
P0138 Chevrolet OBD Error Code P0138 Kia OBD Error Code P0138 Subaru OBD Error Code
P0138 Chrysler OBD Error Code P0138 Lexus OBD Error Code P0138 Toyota OBD Error Code
P0138 Dodge OBD Error Code P0138 Lincoln OBD Error Code P0138 Vauxhall OBD Error Code
P0138 Ford OBD Error Code P0138 Mazda OBD Error Code P0138 Volkswagen OBD Error Code
P0138 GMC OBD Error Code P0138 Mercedes OBD Error Code P0138 Volvo OBD Error Code

Hyundai P0138 HO2S12 Circuit High Voltage – Car OBD Codes

In the case of a Hyundai, the OBD2 code P0138 is defined as follows: The Heated Oxygen Sensor (2), which is placed at the back of the catalytic converter, gives an output signal that is proportional to the ability of the catalytic converter to store oxygen. The signal produced by the Ho2S 2 sensor is less active than the signal produced by the front oxygen sensor. HO2 Sensor voltage must be more than 999 mV for more than 2 minutes (duration varies depending on model) before this code is activated.


Hyundai P0138 OBD code symptoms that may occur include With the exception of MIL lighting, there may be no apparent symptoms. A possible increase in fuel pressure may cause the system to become too rich.


There are several possible causes for OBD code P0138 Hyundai. A code P0138 Hyundai may indicate that one or more of the following events has occurred: The oxygen sensor is faulty. In the O2 sensor signal circuit, there is a short to the battery voltage. High fuel pressure is a problem (not as likely)

Possible Solutions

Here are some suggestions for potential solutions: O2 sensor should be replaced.

Identify and correct a short in the battery voltage of the oxygen sensor signal circuit.

The OBD2 Code Information Be Applicable For Hyundai:

Hyundai i30, Hyundai i20, 2013 Hyundai Sonata Hyundai Santa Fe, model year 2013. Hyundai Langdong, model year 2013. Hyundai HB20X, Hyundai HB20S, 2013 Hyundai HB20X, 2013 Hyundai HB20S, Hyundai HB20, model year 2013. Hyundai i40, model year 2012. 2011, 2012, 2013 Hyundai ix35, 2012, Hyundai ix20, 2011 Hyundai i10, 2011 Hyundai Verna, 2011 Hyundai Santa Fe, 2011 Hyundai Tucson, 2011 Hyundai Santa Fe Sport. Hyundai Sonata, Hyundai Azera, 2011 Hyundai Sonata, 2011 Hyundai Azera, Hyundai Avante, model year 2011.

  • Hyundai ix55, model year 2009.
  • Hyundai Sonata, model year 2009.
  • Hyundai i30, model year 2008.
  • Hyundai Veracruz, model year 2007.

(2007) Hyundai Coupe, (2006) Hyundai Getz, (2007) Hyundai Sonata, (2007) Hyundai Veloster, (2007) Hyundai Sonata Sport, (2007) Hyundai Veloster, (2007) Hyundai Sonata Sport, (2007) Hyundai Sonata Sport, (2007) Hyundai Sonata Sport, (2007) Hyundai Getz, (2007) Hyundai Sonata Sport, Hyundai Tucson, model year 2005 Hyundai Trajet, Hyundai Terracan, 2005 Hyundai Trajet, 2005 Hyundai Terracan, Hyundai Sonata, model year 2005 Hyundai Santa Fe, model year 2005 Hyundai Portico Concept from 2005.

Hyundai Matrix, model year 2005 Hyundai HED 1 Concept from 2005.

Among the Hyundai models available are the Atos Prime (2004 model), Accent (2004 model), CCS Concept (2003 model), and Sonata (2004 model).


1. The list of vehicle manufacturers on the right-hand side of the display screen. The Hyundai brands are represented by the ODB-ii codes that are currently in use. 2. Use the search box to look for any other OBD II Trouble Codes that may exist. In the search box, type in the five-character problem codes and hit the “Search” button. Remember that a particularOBD-II code does not always represent the same thing across different vehicle manufacturers, since there are numerous different manufactures specific codes in use.

This is because not allOBD2 codes used by one manufacturer are also used by other manufacturers.

The material included on this website is provided solely for the purpose of providing general information.

If you have any questions or concerns about the repairs on your car, please speak with your mechanic.

P0138 Code: Oxygen Sensor Issue (Symptoms, Causes, and Fixes)

The most recent update was made on December 31, 2021. When your check engine light illuminates, it might indicate anything from a catastrophic problem with the motor itself to a faulty sensor connection on your vehicle. Therefore, it is critical to run the codes and check what is going on beneath the hood of your vehicle. Are you looking for a reliable online repair manual? The top five choices may be found by clicking here. The code P0138 indicates that there is a problem with the oxygen sensor in Bank 1, Sensor 2.

When a sensor fails to operate properly and a code is shown, it is easy to dismiss the problem.

However, if the problem is not treated immediately, it might indicate a more significant problem with your engine, which could be both costly and dangerous if left unattended. Continue reading to find out more about the P0138 code and the best way to resolve it in your vehicle’s computer system.

What Does Code P0138 Mean?

P0138 is an OBD-II trouble code that describes a high voltage in the oxygen sensor circuit (Bank 1, Sensor 2) Having a P0138 code stored in your car signifies that the downstream oxygen sensor has seen a high voltage reading. When the voltage at this sensor is high, it indicates that the balance of fuel to air in your engine is out of whack, which is dangerous. For the ideal oxygen-to-fuel ratio, a consistent voltage reading of around.45 volts is appropriate. When the sensor voltage exceeds 1.2, the code P0138 is displayed on the display.

See also:  What is a car lease Money factor?

Consider the following codes: Trouble Codes P0131, P0134, P0135, and P0137.

Symptoms of Code P0138

If your vehicle displays the Code P0138, you’ll most likely notice that something is wrong with it immediately. The most evident indicator is the illuminated check engine light. Other symptoms, on the other hand, will establish that there is a problem. It is possible that your fuel efficiency will decline. Your car will operate at a high level of efficiency with this code. This indicates that there is an excessive amount of gasoline and an insufficient amount of oxygen passing through the engine with each stroke.

It’s possible that you’ll notice heavier odours coming from your exhaust whether you’re driving or idling.

Another possibility is that you’ll have a really harsh idle.

It appears that something more serious is occurring to your automobile.

Causes of Code P0138

When utilizing a code to diagnose a problem in your automobile, it’s preferable to start with the simplest and most easily-fixed issue that might be affecting the code and work your way up from there. After determining that this is not the problem, go down a list of more significant issues that require more difficult remedies. A P0138 error code indicates that the voltage measurement from your oxygen sensor is incorrect. It’s likely that the high reading is caused by a faulty connection surrounding the sensor’s area of operation.

If your oxygen sensor is broken or damaged, it might result in a P0138 error code being displayed.

Cleaning your catalytic converter with a cleaner made specifically for the purpose would almost certainly resolve any residual troubles you are experiencing.

When the fuel pressure is high, more gas is forced through the engine, which has an effect on the oxygen ratio. A problem with your fuel pressure is a considerably more serious concern than a mistake with the sensor or connections in your vehicle.

Is Code P0138 Serious?

When your car displays the P0138 error number, driving short distances is not an issue. However, you should not let it continue for an extended period of time without investigating the underlying reason of the error code in the first place. A greater fuel-to-oxygen ratio in the engine does not result in immediate harm to your vehicle’s engine. It will, however, decrease your fuel economy and may cause your exhaust to be less clean as a result. Running your engine at a high RPM for an extended period of time will eventually damage your vehicle.

How to Fix

If you have a P0138 code, the cost and work needed in removing it are determined by the underlying issues that caused the reading to be given to you. In the first instance, repair or replace any broken connections or cables that surround Bank 1, Sensor 2. The majority of the time, this operation eliminates the code with the least amount of expense and effort. Diagnosing and repairing the oxygen sensor itself is the second step in the process. The voltage value should be in the vicinity of 0.45.

If it reads 0.9 or higher, it is possible that the sensor has been damaged and must be replaced.

Check to make sure that both the coolant temperature and the fuel pressure are within the recommended ranges for your vehicle’s operating conditions.

Toyota Prius P0138 Trouble Code Finally Solved, The Results Blew My Mind

I’m willing to bet that no Prius owner wants to be inconvenienced by their vehicle. I am also a member of the group. I want to be able to enjoy my Prius without having to worry about anything. When I just purchased a Prius for $600, it had been beaten to a pulp. Because it was unclean and infested with difficulties, it could not be started. I was eager to start driving it as soon as I was able to get it up and running again and clean it. After a short period of time, the P0138 error code was shown.

Here’s what I discovered about the issue code and what it required to get it to go away.

P0138trouble code is an abbreviation for oxygen sensor high voltage, which is the direct translation.

I know from my own personal experience that I have regarded a high voltage as a short circuit.

It’s hardly a huge deal, is it?

When it doesn’t work, that is.

You could feel apprehensive or stressed about it, and you might even have a brief meltdown.

That’s exactly what I did in this case.

Technicians who are familiar with the operation of these onboard sensors will perform a new set of tests on the system.

All of the data I was able to get with my factory scan tool indicated that everything was in functioning order.

I was perplexed as to why the light was on if everything was functioning properly.

One of the finest brains of this age to whom I have had the opportunity of reaching out is a Canadian friend of mine, who will remain anonymous for the time being in order to preserve his or her identity from disclosure.

As I began to converse with him, as well as with another buddy, It came to and become evident that even though the scan tool may be indicating correct sensor performance, the Toyota sensors might still be bad.

Essentially, this is what everything comes down to.

Prius, Yaris, and Rav4 models include an electronic control unit (ECU) that looks at the upstream or principal Air/Fuel ratio sensor and determines what the engine should do based on that data.

So that sensor should cause the check engine light to illuminate, shouldn’t it?

The information is then received from the rear oxygen sensor, which is responsible for verifying the effectiveness of the catalytic converter.

This is not correct.


The Message of the Story The conclusion of this story is that you should never shoot the messenger.

The primary sensor serves as the foundation for all of the fuel trim calculations performed by the ECU.

From that perspective, I believe it makes sense to have a sensor sound the alarm on the other sensor when it fails, allowing you to pinpoint the source of the problem.

Please accept my thanks for taking the time to read this and find the material valuable.

Watch the video presentation of the Toyota RAV4 Plug-in Hybrid Prime for 2021 and click here to subscribe to the Torque News YouTube channel for daily automotive news analysis and commentary.

He graduated with honors from Weber State University with a Bachelor of Science in Automotive Service Technology.

Peter is also a professor of Automotive Technology at Columbia Basin College in Portland, Oregon. Peter may be reached through his LinkedIn profile, and you can follow him on Twitter at @The hybrid guy. His Facebook page may be found at Auto Consulting from a Certified Professional

Leave a Comment

Your email address will not be published. Required fields are marked *