Temperature gauge drops when driving? (Suits you)

The most probable reason why your car temperature gauge drops while you are driving is that your thermostat stays open. Your car’s thermostat will open and close while you are driving. When it is stuck at the open position, what happens is that the coolant will continue to flow through.

  • The reason the temperature gauge drops when driving is because there’s much greater airflow through the radiator when you’re at speed than at idle. That increased airflow drops the temperature on the coolant coming into the engine. What Will Cause the Temperature Gauge to Go Down

Why does my temperature gauge go down while driving?

The reason the temperature gauge drops when driving is because there’s much greater airflow through the radiator when you’re at speed than at idle. That increased airflow drops the temperature on the coolant coming into the engine.

Why is my car getting cold while driving?

The most common reasons for the temperature to remain low include: A thermostat stuck open. A bad engine coolant temperature sensor. A locked fan clutch.

What causes low engine temperature?

Low coolant, a clogged radiator, bad water pump, and a handful of other things could all be a potential issue. Replacing a thermostat is much easier than replacing an engine, so keep an eye on your temperature gauge.

What are the signs of a bad water pump?

Five Signs Your Water Pump Is Failing

  • Overheating. A dead or dying water pump cannot circulate coolant through your vehicle’s engine and, as such, the engine will overheat.
  • Coolant Leaks. Coolant leaks from the water pump are common and a clear sign that it’s time to replace the pump.
  • Corroded Water Pump.
  • Whining Noises.

What are signs of a bad thermostat?

5 Symptoms of a Bad Thermostat (and Replacement Cost)

  • #1 – Temperature Gauge Reading Higher (or Lower) Than Normal.
  • #2 – Sudden Air Temperature Changes Inside Vehicle.
  • #3 – Coolant Leaking.
  • #4 – Rumbling Noises.
  • #5 – Heater Malfunction.

Why is my temperature gauge stuck on cold?

The most common reason your temperature gauge staying on cold is a faulty coolant temperature sensor. It can also be caused by bad wirings between the cluster or the sensor. In some cases, it can also be a stuck thermostat causing the engine not to heat up properly.

Why does my car overheat at idle but not when driving?

If your car begins to overheat when idling, but the temperature gauge moves back down once you get going, it’s most likely due to a broken radiator fan. However, when your car is sitting still, the radiator fan should kick in, keeping the air moving over the radiator to help cool down the coolant.

Can you drive with a bad thermostat?

Can I Still Drive with a Bad Thermostat? The easy answer to this question is no. While your car may be physically able to move and get you from Point A to Point B, you will want to refrain from operating your vehicle. This can lead to more parts of your vehicle being damaged, especially if the engine is overheating.

What sensor controls the temperature gauge?

To troubleshoot your car’s temperature gauge, you need to know how it works. The temperature gauge reading starts out as a reference voltage that is sent to the coolant temperature sensor. This sensor is nothing more than a thermistor — a variable resistor that changes resistance with temperature changes.

Why is my coolant reservoir boiling and overflowing?

One of the most common causes is a blown head gasket, in which the air pressure inside the cylinder heads is transferred to the cooling system. This escaped air causes bubbling in the coolant/antifreeze reservoir, which can often be mistaken for boiling.

Temperature gauge drops when driving

If your temperature gauge increases when your car is idle but reduces when you are driving, the most likely explanation is a thermostat that has been jammed open. Driving lowers your vehicle’s internal temperature since the amount of airflow across the radiator is significantly more than at idle while you’re moving at a high rate. Because of the increased airflow, the temperature of the coolant entering the engine is lowered.

Read more

The job of the thermostat

When you initially turn on your car, the thermostat is closed to prevent overheating. Once engine coolant reaches a temperature of around 150°F, the thermostat begins to open, enabling coolant to circulate through the engine. Like you drive, the thermostat operates as a valve, slightly opening and shutting in response to the temperature of the coolant. During a cold, winter day, for example, your thermostat may be nearly completely closed since the coolant entering the engine will be significantly colder, and the thermostat wants to maintain coolant flow down in order to avoid overcooling the engine.

Engines perform best when the temperature is approximately 200°F.

If the temperature rises over about 220°, it has the potential to irreversibly harm internal engine components.

What causes a thermostat to stay open?

A thermostat is a mechanical mechanism, and like any mechanical device, it can break down. The rubber seal in the pellet that permits coolant to mix with the wax is the most often seen failure. While driving, this results in the thermostat remaining open the whole time, which prevents the engine from hitting 200 degrees Fahrenheit. Idling causes the engine to heat up to a higher temperature than when it’s not running.

Fix for stuck open thermostat

The only way to fix a thermostat that is stuck open is to replace it, according to 2020. Rick Muscoplat is a professional musician. Rick Muscoplat posted a blog entry on

What Will Cause the Temperature Gauge to Go Down While You Drive & the Heat Not to Work?

Photographs courtesy of DC Productions/Photodisc/Getty Images Although the cooling system in your vehicle’s engine is not the most intricate system on the vehicle’s engine, it is nevertheless susceptible to failure over time. The water pump and thermostat are the two most complicated components of the cooling system, which implies that a failure will almost always occur in one or the other of these components. Low coolant temperatures on a consistent basis can only signify one thing; thankfully, the necessary components are rather inexpensive and simple to install.

Cooling System Basics

The cooling system of an engine begins with the water jacket, which is composed of a series of empty chambers that are strategically arranged around the cylinders and in the cylinder heads. The water pump draws water from the water jacket and pushes it through the radiator tubes, allowing it to enter the radiator through the radiator tube opening.

When the engine is cold, a thermostat valve cuts off the top radiator line, causing coolant to cycle through the block until the engine is warmed up once more.

Heating System

The heater core is a type of small radiator that is housed within the climate control duct of your vehicle. In addition to a tiny outlet on the pressure side of the water pump that feeds water through the heater core, when the heat is turned on, a valve in the heater core’s water intake line opens and allows coolant to flow through the core as well. The thermal energy for the core, and hence for the heating system, comes from the cooling system of the vehicle’s engine.

Thermostat Failure

It is possible for thermostat valves to fail in one of three ways: they can be either open or closed, or they can become stuck halfway open. If the valve becomes stuck in the closed position, coolant will continuously recycle through the engine without reaching the radiator, causing the engine to overheat as a result. Under load, a stuck-halfway valve will increase the amount of time it takes for your engine to warm up and will cause temperatures to steadily rise as the engine warms up. A stuck-open thermostat will continuously circulate coolant through the radiator, regardless of the temperature of the coolant.

Location and Testing

To locate the thermostat, follow the top radiator hose to the housing where it joins to the engine and then back to the thermostat. When you remove the housing from the block, you’ll discover a saucer-shaped thermostat wedged between the two pieces of metal. The thermostat valve should be closed; if it is even slightly open, the thermostat should be discarded and a new one purchased.

Replacement Thermostats

Replacement thermostats are available in a variety of temperature ranges, and you may normally adjust the engine temperature by 10 degrees either up or down depending on the application. For example, if you tow a lot, you may want to use a 170-degree thermostat instead of the suggested 180-degree thermostat, or a 190-degree thermostat if you want to gain a little more horsepower while also increasing the warmth of the heater output. References

  • In addition to ‘Auto Fundamentals’ by Martin Stockel from 2005, ‘How to Rebuild Small-Block Chevy LT1/LT4 Engines’ by Mike Mavrigan from 2002 is also recommended.

Bio of the AuthorRichard Rowe has been writing professionally since 2007, with a particular emphasis on automotive issues. As a tractor-trailer driver and technician, as a rigger at a fire engine plant, and as a race-car driver and constructor, he has a diverse range of experience. Rowe attended Central Florida Community College, where he majored in engineering, philosophy, and American literature.

More Articles

It ‘sounds’ as though, based on your account, your thermostat is only partially open when the engine has cooled to typical operating temperatures. Whenever you’re driving down the road, more air is being forced through the radiator than when you’re sitting still. This indicates that the cooling capacity has been improved (more air equals better cooling capability). If the thermostat is functioning properly, it will only allow as much heated coolant to be removed from the engine and as much cooler coolant to be introduced into the engine as is necessary to keep the engine operating at the proper temperature for safe operation.

It will not harm the engine in and of itself, but it will reduce overall fuel mileage, which will have a negative impact on your wallet in the long run.

While I don’t advocate that you go out and change the thermostat right away, I do strongly advise that you get it checked to make sure it’s functioning properly before proceeding.

Why My Car Temperature Gauge Drops While Driving? (Solved!)

Once a motorist learns to drive, one of the most crucial lessons he or she learns is to make sure that their temperature gauge never reaches red since that is when the engine begins to overheat. However, not many individuals are taught the importance of keeping their temperature gauge somewhere in the usual range and without sliding into the cooler zone of the dial. The reality of the matter is that your engine has to be warm in order to perform optimally.

So, if that is the case, why are there instances where your car’s temperature gauge drops when you are driving?

The most likely explanation for why your car’s temperature gauge lowers while you’re driving is because your thermostat is left open while driving. While you are driving, the thermostat in your car will open and close automatically. It is important to note that while the valve is stuck in the open position, coolant will continue to flow through. While it may be a good idea to keep your engine cold rather than hot, it is important to remember that you are always required to keep the temperature of your vehicle at a standard level.

Therefore, if the temperature gauge on your automobile begins to dip while you are driving, it is critical that you address the matter as soon as possible.

Is it normal for the temperature gauge to fluctuate?

For those who have been taught how to properly care for a car, one of the things they are taught is to keep an eye on the temperature of the engine. That means you’ll have to keep an eye on it via the temperature indicator on the dashboard. And, most of the time, we are aware that the engine should not be running at excessive temperatures while we are driving, otherwise we run the risk of causing damage. For example, we know that we should ensure that the temperature is within a reasonable range by placing the pointer close to the middle of the temperature gauge or by ensuring that the temperature is between 190 and 220 degrees.

  1. While driving, this should remain constant because the coolant in the engine performs its function by ensuring that the engine remains cool regardless of how hard it is working.
  2. For starters, it is normal for the temperature displayed on the temperature gauge to fluctuate up and down from time to time as long as the differences are minor and small.
  3. Is this a usual occurrence?
  4. If you want to make sure that the engine’s temperature is perfectly fine and that the gauge is functioning properly, the temperature gauge should only be somewhere near the middle of the gauge and may rise and fall in small increments as the engine temperature changes.

You must therefore ensure that the temperature gauge on your car is not acting erratically and that it is only moving up and down in smaller increments.

  • If my temperature gauge is in the middle of the scale, should I be concerned? (From the Beginner’s Guide)

Why does my car temperature gauge drop while driving?

When we talk about how the temperature gauge should never reach dangerously high readings since this indicates that the engine is overheating, we all know that this is something that is fundamental among many various types of drivers. However, not many drivers are aware that the opposite extreme instance should not be considered usual as well, especially while they are behind the wheel. What we’re saying is that there shouldn’t be any situations in which the temperature gauge in your automobile goes to dangerously low levels while you’re driving.

  1. Of course, you must be aware that the temperature gauge in your automobile must be operating at normal levels in order for the engine to perform at peak performance.
  2. You should also be aware that your engine must be allowed to warm up before the lubrication can be distributed throughout the engine’s various chambers.
  3. Additionally, this might result in engine damage because your engine must be adequately oiled in order for it to operate correctly.
  4. This is due to the fact that the engine should be creating heat while it is burning through gasoline and air, as well as while its moving parts are producing heat through friction.
  5. In light of the foregoing, what may be the cause of your car’s temperature gauge lowering while you’re on the road?
  6. The thermostat’s function is to open when the coolant temperature reaches 150 degrees and the coolant begins to heat.
  7. For example, consider the winter months.
  8. As a result, the thermostat is more likely to remain closed because there is no need to allow additional coolant to flow into the engine because the cold weather is sufficient to keep your engine operating at normal temperatures.
  9. As a result, even if the engine is operating at normal temperatures, a thermostat that has become jammed open will continue to allow coolant to flow into the engine.
  10. Because a thermostat is a mechanical component, it is just as susceptible to wear and tear as any other component in your automobile.
  11. As a result, there may be situations in which the thermostat becomes stuck in the open position and continues to allow coolant to flow into your engine even though your engine should be becoming warmer as you drive.
  • Continue reading:What Causes the Temperature Gauge in a Car to Rise? (TroubleshootingFix)
See also:  P0013 or P0014 Equinox after an oil change? (Correct answer)

What should I do if my car temperature is low?

If you find that the temperature in your car is running too low while you are driving, do the following tests first before attempting to have your thermostat replaced:

  • To begin, open the hood of the automobile and remove the radiator cap before turning on the ignition. Make an effort to keep an eye on the coolant since, in most situations, it should not be moving. This is due to the fact that while the engine is cold, the thermostat should remain closed and should not be allowing coolant to flow through it. Start the engine of the vehicle. Keep note of how long it takes the engine to warm up or to provide enough heat, even if the heater is left on all the time. After more than five minutes, the heater has not produced enough heat to be considered functional. The thermostat has been left open, which is a logical conclusion. This is due to the fact that, if the coolant is allowed to run freely, it would take a significant length of time for your engine to be able to generate enough heat

There is no simple fix for your automobile if you have confirmed that the thermostat is stuck in the open position, and you have confirmed that the thermostat is in the open position. If you have this problem, the only solution is to take your automobile to a technician and have the thermostat changed with a brand new one. It is likely that failing to address the problem as quickly as possible can result in damage to your car’s engine, particularly if the engine is unable to work at normal temperatures.


RX Mechanic: The temperature gauge on the car rises and falls. It continues to run since the temperature gauge is down and the drive heat is not working. Risks Free Auto Repair Consultation: When driving, the temperature gauge decreases.

Can You Drive With A Bad Coolant Sensor? (Solved!)

Vehicle Mechanic: The temperature gauge on the car fluctuates. Although it continues to run, the temperature gauge is down, and the drive heat is not working. Risks Assistance with Auto Repairs for No Cost: When you’re driving, the temperature indicator goes up.

What Does Temperature Coolant Sensor Do?

This little but critical piece of equipment is known as the engine coolant temperature sensor (ECT) or coolant temperature sensor (CTS) in your car. The sensor itself isn’t particularly noteworthy. It is made of brass to avoid corrosion and is small enough to nestle comfortably in the palm of your hand. The information it provides, on the other hand, is crucial to the operation of your car. The engine management system receives real-time engine coolant temperature data from a sensor mounted to the engine near the thermostat housing.

The PCM (Power-train Control Module) depends on this information to make a variety of critical choices about fuelling, cooling, power application, and emission levels, among others.

The little temperature sensor is critical to the operation of your motor.

How Does Coolant Sensor Work?

The sensor is made up of two parts: an electrical connector end and a sensor probe end. A simple threading operation is used to insert the sensor into the engine, with the probe end submerged in coolant within the engine. The sensor functions by altering resistance in a proportionate manner to how hot the probe end of the sensor becomes. When the sensor is cold, it will measure around 10,000 ohms, and when the engine is up to operating temperature, it will read approximately 200 ohms. Don’t get too caught up in the details.

  1. It’s a piece of cake!
  2. The sensor is supplied with 5 volts via a single cable.
  3. The second wire is responsible for returning the lower signal voltage to the PCM.
  4. The PCM utilizes this lower voltage to determine the temperature of the coolant in the radiator.
  5. It’s important to note that not all sensors operate in this manner.
  6. A temperature coefficient that is positive is inverted.
  7. Some sensors may have a three-wire configuration; nevertheless, this should not be a source of concern.

In addition, some higher-end versions may have more than one ECT in use. Each bank of a V engine may be equipped with an ECT. Some systems make use of two ECTs, one for the PCM and the other for the radiator fan, as shown in the diagram.

Can Bad Coolant Temperature Sensor Cause Car To Stall?

The symptoms of a faulty sensor might vary, but the common denominator is the presence of a check engine light. It is a very essential sensor. As soon as the onboard computer detects a problem, the engine light will illuminate to inform the driver. Knowing that the sensor is critical to how engine control modules make judgments regarding fuelling, a faulty reading will result in poor performance, with stalling being one of the most common symptoms to be seen. Other frequent signs and symptoms are as follows:

  • Gas is expensive
  • There is a strong gas smell
  • The car is difficult to drive
  • Hesitation when accelerating
  • A high or low idle
  • Misfiring
  • Black smoke
  • A foul odor coming from the exhaust pipe
  • The engine is overheating. The fan is always running, and the HVAC system is blowing cold air.

How To Test A Coolant Sensor

Try putting a little amount of pressure to the gas pedal to signal the PCM to override and supply some gas if your car won’t start from cold. If the engine now starts, you have most likely identified the source of the problem. My more common method of diagnosis begins with a visual examination. Checking for simple, straightforward victories. In the event of a malfunctioning ECT, I will look for items such as:

  • Coolant level
  • If there is insufficient coolant, the sensor will perform sporadically, if it operates at all. Looking for a loose wire connector is on my list of things to do today. Damage to the coolant sensor wire, such as chafing or rat damage
  • A faulty coolant state might cause the sensor to coat, resulting in a false reading.

After I’ve checked off all of the low-hanging fruit, I’ll shift my focus to the DTCs. Modern automobiles, as you are aware, record any severe errors in the powertrain control module (PCM). It seems reasonable to begin your diagnostic with such information. As a result, you will need to borrow or purchase a code reader, which will be necessary. Take a look at the bidirectional scanner that I propose on theAuto electrical repair toolspage of my website. The following are examples of ECT trouble codes:

  • P0115 indicates a circuit fault
  • P0116 indicates a circuit range
  • P0117 indicates a low voltage
  • P0118 indicates a high voltage
  • And P0119 indicates an intermittent fault.

When testing a sensor, PCM, and its circuit, a scan instrument that can read live data will be required. These tools are a step up from a simple code reader, but they are still not prohibitively costly, and they will more than likely pay for themselves several times over. Here are some simple tests you may run to aid in the diagnosis of a defective ECT sensor. It’s important to remember that sensors aren’t that costly, and while I’m not in the habit of tossing parts at cars, I realize that it doesn’t make sense to spend money on diagnostic equipment to analyze a $20 item.

Testing ECT resistance

This test can be carried out either inside or outside of the vehicle. The results, on the other hand, will not be decisive. A decent scan tool has the capability of graphing ECT performance and makes it simple to identify interference or a signal that has dropped out for a brief period of time. When using a voltmeter, it will be difficult to detect an intermittent defect. However, this test will be quite effective in the case of a dead sensor. Remove the sensor plug using a DVOM set to ohms and go to the next step.

Reconnect the sensor and allow the engine to idle for a few minutes before turning it off.

A sensor with a negative coefficient that is operational will read a lower resistance value.

Of fact, a lower resistance value does not always imply that the sensor is not malfunctioning.

The resistance range of your car’s sensor will be provided for a given temperature range in your vehicle. It is possible to successfully test the sensor with a thermometer, a spec chart, a DVOM, and hot water, among other tools.

Testing ECT volt drop

As you are aware, the coolant sensor receives a 5v reference supply from the PCM, as you can see in the image below. The second wire is the signal wire, which is responsible for returning the lower voltage to the PCM. As the engine heats up, the resistance in the sensor decreases as well. The ability to view the sensor’s operation in real time is provided by measuring the volt drop across the sensor. To execute the test, the engine must be operating at all times, and the test must be done through the whole heat cycle.

ECT reference voltage check

This test is an easy verification of the reference voltage. We’ll have to unhook the sensor while the car is still running. Back probing is the most effective method. It is possible to cause contact points to spread if you apply too much force to them. A voltage of 5 volts or close to it indicates that everything is in working order. You can see the tools I use on theAuto electrical repair tools page, which you can find here.

What Happens If You Unplug The Coolant Temp Sensor?

Attempting to unplug the engine coolant sensor while the vehicle is in motion would most likely result in the engine stumbling and running rough. Although the engine light may not illuminate immediately, a DTC (Diagnostic Trouble Code) will be recorded in the vehicle’s computerized management system. You may also notice that the engine fan cycles on and off on a regular basis. Because the engine will be running rich, you may smell raw gas and possibly see black smoke coming out of the tailpipe.

This is especially probable on a chilly morning when starting the engine.

How To Replace A Coolant Temperature Sensor

A simple set of tools, such as the ones listed below, will make the task of replacing the sensor much easier.

  • Disposable drain pan
  • Small flat screwdriver
  • Deep socket and ratchet
  • New coolant
  • Clean cloths

You can get the professional-grade equipment you need right here on our Coolant system tools page! In addition, if you require high-quality coolant sensors, please see the Amazon link below. Sensors for Auto Coolant on Amazon According to what you may already be aware, the sensor is positioned near the thermostat housing on the majority of models, and the technique is as follows:

  • Place a drain pan under the engine
  • Some coolant will leak from the ECT housing if the engine is not running. Preparing the replacement ahead of time will help you to limit the mess to a bare minimum. Remove the electrical plug connector by prying it out with the flat screwdriver (if necessary). Set aside and avoid allowing coolant to get into touch with the contact pins. Remove the sensor by removing it with the deep socket and ratchet
  • Before tightening the sensor ad washer (if appropriate), it is necessary to manually fit it. Please be delicate with this because it is not a lug nut and it is brass. Most are torqued to around 15 lb ft, but verify the manufacturer’s specifications for your specific model. If the sensor does not come with thread sealer, you can use some pipe dope to seal the threads. Replace your electrical connector if it is damaged. Refill your coolant reservoir
  • Start the car and look for signs of heat coming from the heater. Depending on how much coolant you lost, you may need to bleed the system. If the system becomes air locked, you run the danger of causing damage to the engine. If you are interested in learning more about that specific process, you can see my post ‘No heat at idle’ here.
See also:  Test Brake Fluid Condition? (Suits you)

Related Question

In what range does the cost of replacing a coolant temperature sensor fall? A coolant temperature sensor may be purchased for between $20 and $50 dollars. A coolant sensor installation may cost between $100 and $250 at a garage. In most cases, changing the coolant and purging the coolant system of trapped air will be required in order to install the sensor.

Temp gauge spikes randomly.

  • Date of joining:June 16, 2014 Member:132101 Messages:56 Gender:Male Jeff’s first name is Jeff and he lives in Southeast Utah. Vehicle: 1998 Toyota Tacoma V6 3.4 TRD 4×4 5-speed, with 100k miles on it. At the very least, I believe it is random. That is exactly what I have experienced several times in the last month while traveling on the highway. When my rig is completely warmed up, the temperature gauge will normally be exactly in the center, but it will abruptly shoot up to the red line and then fall back down to the middle, and then a few seconds later jump about halfway up and then fall straight back down. It will continue in this manner for a few minutes, leaping to random locations between the middle and the red, and then it will ultimately stop, and it will not occur again for several days after that. It is always in the UP position. It never deviates from the mid-point of the graph (which I read elsewhere might indicate the sensor is losing power). The pace at which it jumps varies depending on the situation: sometimes it is really fast, other times it is a little slower. However, it does not move in a manner that suggests the engine is truly overheating: it moves slowly and steadily. But today was different because it did a little amount of crawling as it ascended, but then it would just tumble back down. This was the first time this has happened. The problem does not appear to be tied to speed or RPMs, with the exception of today, when the moments when it snuck up on me were while I was speeding. However, as I take my foot off the gas pedal, the speed of the car increases. The pattern I’m looking for doesn’t appear to exist, and I’m not sure why. As a result, I’m completely perplexed. I checked this topic and other boards for difficulties others have had with their temperature gauges and found a few that match the bill, but nothing that truly fits the bill here. Thoughts? Thanks

Canyon JeffWell-Known Member

  • Date of joining:June 16, 2014 Member:132101 Messages:56 Gender:Male Jeff’s first name is Jeff and he lives in Southeast Utah. The vehicle is a 1998 Toyota Tacoma V6 3.4 TRD 4×4 5-speed with 100,000 kilometers. SO, I’ve had some additional time to consider this issue, and I believe I’ll be able to contribute some of my views to this thread. I’m not very knowledgeable when it comes to electrical wiring. Really, there is nothing. However, I believe that the ECT sensor is the source of the problem. However, I am unsure if the problem is with the sensor itself or with the cabling that connects the sensor to the rest of the system. Here’s what I do know about the subject. My truck also has a slew of other small annoyances that I’ve been working on slowly but steadily. One issue that I recently handled was the well-known puking front differential breather hose on the vehicle. In the meantime, a huge amount of junk had built up in the electrical wires that run alongside the breathing pipe, which I had to remove before I could fix it. The purpose of those cables is beyond my comprehension, however I did note that this problem occurred practically immediately after a particularly massive gear oil vomiting occurrence. Another thing I discovered a LONG time ago was that the jiggling of those wires would occasionally cause the temperature gauge to rocket all the way up to the red line even when the engine was entirely shut off, with no key in the ignition or anything else in place. More jiggling of those wires would lead the gauge to drop back to its previous level. That was DEFINITELY an electrical problem, and I’m wondering whether these two issues are connected in any way. but how exactly.? I’m not even sure where the ECT sensor is located on my vehicle, and it’s getting late here, so I’ll attempt to locate it first thing in the morning the next day. Anyone who wishes to add their thoughts in the meanwhile is welcome to do so. Thank you very much, gentlemen.

DrZWell-Known Member

  • Date of joining: December 14, 2014 Member:144262 Messages:1,458 Mesa, Arizona is a city with a male gender. Vehicle: 1996 2.4L 5-speed transmission For the ECU/EFI system, there is a coolant temperature sensor, and there is a separate coolant temperature sensor for the gauge. There are two separate sensors. I assume there are two solenoids in the temperature gauge in the instrument cluster. If one solenoid receives steady power while the ignition is turned on, it drags the needle down. The other solenoid gets electricity through the resistance of the temperature sender gauge and raises the needle of the thermometer to the desired temperature. As a result, if the first solenoid’s connection to ground is severed, the needle will go upward. If the sender gauge (or its wiring) fails to function properly, the gauge needle will rise as well. As a result, inspect the wire leading to the temperature sender. I believe this sensor has only one wire linked to it, which I feel is correct (as opposed to the ECU temp sensor which has 2). Another option is that the nuts that hold the gauge to the rear of the cluster are loose or have some small rust on them, and because the nuts are responsible for the electrical connection, this might be the source of the problem.

Canyon JeffWell-Known Member

  • Date of joining:June 16, 2014 Member:132101 Messages:56 Gender:Male Jeff’s first name is Jeff and he lives in Southeast Utah. The vehicle is a 1998 Toyota Tacoma V6 3.4 TRD 4×4 5-speed with 100,000 kilometers. Thank you for your response, DrZ. Using information from a yotatech article, I was able to determine the location of the temperature sensor for the gauge. There appears to be a lot of obstructions along the path, making it difficult to get to. In terms of the instrument cluster, will I have to disassemble the entire dashboard from the inside? I’d never been on that particular voyage before. Is there any suggestions on what to look for on the sender’s end specifically? Do you happen to have a wiring diagram on hand? I don’t believe it. However, I am thinking that there are a number of different areas to look for problems with the wiring. Once again, thank you so much. If I were you, I would look for an OBD2 scanner that allows you to monitor real-time engine information (like aScangauge, or some other hand held unit). Check the scanner’s coolant temperature readings against what your temperature gauge on the dash is displaying to ensure that the dash gauge is really producing inaccurate readings
  • And

o0oSHADOWo0oJust lurking in the darkness

  • Date of joining: May 7, 2014 Member:129360 Messages:8,872 Gender:Male ShadowVa Beach’s given name is ShadowVa Beach. Automobile: 2012 Double Cab Short Bed 4×4 Toyota TRD Sport There are only a few LEDs. Is it possible for you to try changing the thermostat? It’s possible that it’s original or ancient and is clinging

2toysWell-Known Member

  • Date of joining: March 31, 2009 Member:15424 Messages:74 Gender:Male Los Angeles is a city in California. Red Hot Double Taco (Vehicle No. 1) After replacing the head gasket, I’m now suffering the same issue as before. I can see that the temperature on the ascan gauge is normal, but the temperature gauge surges at random. I’m also guessing it’s an electrical problem, maybe a grounding issue, given that it’s a one-wire sensor. Something is bothering me, but I can’t place my finger on it.

mwrohdeWell-Known Member

  • Date of joining: March 12, 2014 Member:125160 Messages:1,045 Gender:Male Matt is his given name. Sugar Hill is a city in the state of Georgia. Toyota Tacoma 4×4 5-speed 3.4 TRD SR5 (2003 model) Once, while the engine was cold, I came dangerously close to overheating it. The coolant flow was stopped, I believe, because one of the radiator hoses had frozen. That might explain why it’s ‘only when it’s cold’ in the first place. Random surges – I’d also replace the thermostat if this happened

2toysWell-Known Member

  • Date of joining: March 31, 2009 Member:15424 Messages:74 Gender:Male Los Angeles is a city in California. Red Hot Double Taco (Vehicle No. 1) What are the three points of contact with the ground? There is one that runs from the firewall to the top of the head. One next to the battery and one near the fender. Located on the intake manifold under the service plug, is the other one.


  • Date of joining: April 26, 2015 Member:153969 Messages:599 Gender:Male First and last name: FirstGenTacomaLoverWashington State Vehicle:1999 Toyota Tacoma SR5 Exta-Cab 4WD V6 in Wine With the exception of Ranch 5000 Shocks and Struts, this vehicle is completely stock. My ancient Toyota Tacoma does the same thing, but only when it is all warmed up and you try to fire it up for the first time. The temperature gauge will abruptly begin to travel into the red zone and then decrease a few seconds later to the green zone. It does this at random, and there is no clear pattern to how it goes about doing it
  • Yet,

SnowyIs neither here nor there

  • Date of joining: February 5, 2014 Member:122349 Messages:2,843 Gender:Male Connor is my first name and I live in Winnebago, Illinois. Vehicle:3 connected 98 Xtra cab pickup trucks Stock-ish Instead of a swing in real temperature, this is a rapid gauge sweep up and down in a random direction. My truck does that as well, despite the fact that the temperature on a data reader remains stable at 190 degrees. There’s definitely a problem with the earth someplace, and I’m not in the mood to go down there


  • Date of joining: April 26, 2015 Member:153969 Messages:599 Gender:Male First and last name: FirstGenTacomaLoverWashington State Vehicle: 1999 Toyota Tacoma SR5 Exta-Cab 4WD V6 in Wine color With the exception of Ranch 5000 Shocks and Struts, this vehicle is completely stock. Snowy, I absolutely agree with you on this point. It is not worth my time to go through everything again. If it did it on a constant basis, I may be able to persuade myself to take it down, but not if it was a sporadic problem. Paul, just take it easy.

AugustusJackWell-Known Member

  1. Date of joining: September 30, 2018 Member:267950 Messages:497 Gender:Male A.J.NW WA is his given name. Car/Transportation: ’19 DCLB OR, 2000 XC 3.4L 4wd MT

Car Temperature Gauge Goes Up and Down: Causes and Fixes

You were heading to work one gorgeous morning when you noticed that your car’s temperature gauge was going up and down constantly. You get quite perplexed and uneasy. And you’re sitting there wondering, ‘How am I going to correct this mechanical error?’. Don’t be baffled by this. That’s why we’re here to assist you in troubleshooting this issue and identifying a diagnostic remedy to it. First and foremost, your car’s temperature gauge is a dial that indicates how hot or cold the coolant in your engine is at any given moment.

There are a variety of factors that might cause this needle on your car’s temperature indicator to wander wildly up and down. Keep reading as we go into further detail about each of these elements.

What causes Car Temperature Gauge to go up and down?

So, you wonder, ‘what is it that causes the temperature gauge in my automobile to fluctuate?’ There are a slew of causes that have contributed to this abnormality. In the majority of situations, one or more of the cooling component’s functional components may have failed. Observing the temperature gauge fluctuating between normal and hot, for example, may indicate the presence of a cheap, fault-sensitive thermostat.

Stuck-Closed Thermostat

Thethermostatis responsible for regulating the temperature of the coolant before it returns to the engine to cool it. Even though the thermostat is generally inexpensive and easily changed, it can create significant problems for your vehicle if it becomes faulty. If it becomes stuck and refuses to open, the coolant will not be able to flow to the engine, preventing it from overheating. This causes the engine to overheat and eventually fail. When the engine begins to overheat, the temperature gauge in the automobile may become heated before returning to normal.

  • It is thus necessary to monitor this level on a frequent basis in order to prevent coolant leaks.
  • If your thermostat is partially jammed, you will almost certainly notice that the temperature of your automobile drops while you are driving.
  • When a thermostat is properly operating, it only permits warm or cool coolant to enter the engine, so controlling the overall temperature of the vehicle’s engine.
  • As a result, it is recommended that you replace the simple thermostat rather than spending hundreds of dollars on gasoline.
See also:  Automotive tools — Which brand to buy? (Best solution)

Engine getting Overheated

Experts have proven that when the temperature of your engine rises beyond 230 degrees Fahrenheit, your engine is considered to be overheated. If the temperature rises beyond 245 degrees Fahrenheit, catastrophic damage to your engine is possible. This is just another reason why you should be on the lookout for an engine that is overheating. An overheated engine, coupled by a considerable loss of coolant, is one of the many possible causes of your car’s engine failing to start, aside from having a faulty battery.

If the problem is not addressed, the pistons will eventually thrust themselves into the cylinder, which will be devastating for the engine of your automobile.

Another comparable issue that you may notice in your automobile is that the temperature gauge on your car quickly rises to dangerously high levels.

You are, to a certain extent, accurate!

It’s possible that your thermostat is malfunctioning, or that your car’s coolant level has dropped. In either situation, there is insufficient circulation of coolant to cool down the operating engine, resulting in the engine becoming overheated and damaging it.

Lousy Radiator Fan

The radiator fan is situated in close proximity to the reservoir tank. When your automobile is not moving quickly enough to take in air, the fan is intended to suck air into the radiator through the radiator. A failed fan can cause your engine to overheat and become irregular in its operation. A faulty radiator fan might result in a temperature gauge that is constantly changing.

Head Gasket Blown

Perhaps you have recently observed that the temperature gauge on your automobile climbs and then drops. The most likely reason of this anomaly is a faulty head gasket, which is the most common scenario. The head gasket, which is located between the cylinder head and the engine block, is responsible for maintaining internal combustion. It makes it possible for coolant and oil to circulate more easily throughout the engine, which is beneficial for both cooling and lubrication. The head gasket can get distorted as a result of severe engine overheating, causing the oil and coolant to mix together and generate oil-coolant mixtures.

Clogs in the cooling system can prevent coolant from flowing properly, resulting in an overheated engine.

If the engine is operated with a blown head gasket for an extended period of time without repair, substantial damage will occur.

When you detect white smoke coming from the exhaust, unexpected coolant loss without a leak, and your engine becoming overheated, you have most likely had a burst head gasket.

Bad Radiator

The majority of drivers have an unpleasant driving experience because their car’s temperature gauge rises when they are idling or in traffic. For drivers, this may be extremely stressful and perplexing. The most likely culprits are a faulty fan and a faulty radiator, respectively. The radiator is responsible for controlling the temperature of the coolant. If you observe sludges forming in the radiator, this indicates that the radiator and its fan have failed and that the radiator and fan must be replaced immediately.

Aluminum radiators are a superior alternative to iron radiators in many ways.

Compared to other materials, aluminum radiators offer significantly more heat due to their excellent thermal qualities.

Whenever the radiator cap on your automobile is not correctly sealed, it allows air to leak into the radiator, causing small air pockets to form in the heater core and radiator hoses.

Radiator caps that have failed can cause an overflowing coolant reservoir, a collapsed radiator pipe, and coolant level leaking, among other symptoms.

Faulty Cooling System

The following are some possible causes of a rising temperature gauge in your automobile without your vehicle overheating: a malfunctioning radiator, low coolant levels, an ill-functioning thermostat, or an ineffective water pump (to name a few). A faulty water pump can also cause the temperature of the automobile to rise abruptly and dangerously. A water pump circulates coolant through the cylinder head and engine block, allowing the engine’s temperature to be controlled and maintained. A malfunctioning water pump will prevent coolant from being circulated throughout the engine when it is in operation.

If there is no immediate action taken, the cylinder head can get deformed and the head gasket can become twisted, resulting in a significant increase in the temperature of the vehicle.

Your cooling system may be defective, which is a typical cause of your car’s temperature gauge fluctuating up and down when no heat is produced.

It is possible that particles or rust have clogged the coolant path.

The most common reason for your car’s temperature gauge to rise and fall while you’re driving is simply because a component in your cooling system is not working properly.

You may either hire a skilled auto repair to take care of these problems, or you can simply replace most of the damaged components yourself.

How To Fix If Car Temperature Gauge Goes Up And Down

If the temperature gauge in your automobile is not working properly, it is imperative that you investigate the problem. Identifying and correcting the problem as soon as possible is essential. Hesitating to make a repair might result in serious harm to your vehicle. The following are some straightforward and doable measures to correct these mechanical faults, as well as a bucket for draining the coolant.

Replacing a Defective Thermostat Valve

As previously said, the thermostat is a low-cost automobile component that, if not changed promptly when it develops a malfunction, can spell disaster for a vehicle. Here’s a simple method for rapidly repairing a malfunctioning thermostat. It is recommended that you obtain the necessary tools before proceeding with the instructions outlined below. A screw jack, a pair of vice grips, screwdrivers of various sizes, an adjustable wrench, an OB2 scanner, a pocket knife, and a tiny ball-peen hammer are among the items in this kit.

  • Allow the automobile to cool down for approximately 15 minutes after you have turned off the engine. The location of the thermostat valve must be determined. In most cases, it is located at the bottom or the top of the car’s radiator. Increase the height of your vehicle in order to have more clearance
  • Remove the radiator cap and set it aside. Drain the radiator and separate the thermostat from the vehicle in a safe manner. Check to see if the thermostat is still in working order. To be sure, submerge it in a basin of hot water and check to see whether the valve opens. If it remains close, it has deteriorated into an inefficient system. Replace the old thermostat with a new one if it is faulty. Before replacing your coolant plugs, double-check that they are all in good condition. When you start the car, look at the dashboard temperature gauge to see whether there has been a significant improvement.

Replacing A Faulty Coolant Temperature Sensor

This sensor is often found around the base of the radiator, where it measures the coolant temperature. A malfunctioning coolant temperature sensor is one of the most prevalent causes of incorrect temperature readings (CTS). Soon after sustaining damage to the CTS, the vehicle begins to experience engine banging. Engine knocking occurs when gasoline burns unevenly in an engine cylinder, causing shocks and noise to be produced as a result of pre-ignition. Typically, the cost of repairing a faulty temperature sensor is between $145 and $195 depending on the manufacturer.

The amount covers both the cost of the part and the cost of the labor to install it. Alternatively, if you want to purchase a new sensor, you could expect to spend between $65 and $90. You must follow the instructions outlined below in order to repair a bad CTS.

  • Using an efficient OBD2 scanner, you may check to see whether the sensor is still functional and determine if it is in excellent working order. Allowing your car to cool down for 20 minutes should solve the problem if the CTS is not working. Increase the height of the car’s front end to gain more clearance. Remove the cap from the radiator
  • Remove all of the coolant/water from the radiator
  • Make certain that the CTS wire connector is disconnected. Remove the defective temperature sensor from its mounting bracket. Replace the temperature sensor with a new one. Reconnect the electrical connector as soon as possible. Begin by starting your engine and checking to see whether the gauge is operational.

Diagnosing Air in the Coolant System

Whenever air is allowed to enter the radiator, it causes the formation of air pockets within the radiator, which results in an unstable temperature within the engine. Overheating of the engine may develop as a result of this. The air may be removed from the system to correct this issue. Follow the instructions below to do so.

  • Lifting your automobile and leaving the bonnet open will provide a better look. Remove the radiator cap and set it aside. In order for coolant to begin to flow throughout the radiator and engine, you must first start your car’s engine. Because of the car’s tilted orientation, the trapped air in the radiator will begin to burp out
  • This is a good thing. It will take approximately 20 minutes to steam up the engine and remove all trapped air
  • However, it may take longer. You are free to proceed with closing the radiator cap and lowering the vehicle. Observe whether there are any burping noises when driving around in the automobile In the absence of noise, you can top up the coolant if the level has gone below a certain point.

If you’ve attempted the three procedures above and your car’s gauge continues to fluctuate, you should seek the assistance of an auto repair for assistance. He would also inspect and repair any other fragile components inside the cooling system as well as any engine parts that needed to be replaced.

Frequently Asked Questions

This just indicates that your engine has become too hot. There are a variety of reasons that might contribute to an overheated engine. These issues may include a low coolant level, a blocked radiator line, a faulty thermostat, a faulty water pump, and a malfunctioning radiator fan, to name a few examples. If the temperature gauge in the automobile has acquired a defect, it is possible that it is the source of the problem.

Q: Is it normal for a car temperature gauge to fluctuate?

Typically, a car temperature gauge is constructed to survive for a long period of time and to gradually climb from the cold to the intermediate temperature. As a result, if you see that the indication begins to fluctuate, you should move quickly to determine what is causing it and correct it as soon as possible.

Q: Should my temperature gauge be in the middle?

After a few minutes of driving, the temperature indicator on the dashboard gradually goes from the chilly to the center. When your car is completely operational, the average level of the temperature gauge is about in the center. Anything that deviates from this standard necessitates immediate action. If the gauge remains cold after the engine has been running for an extended period of time, it might indicate that the automobile gauge has failed or that the thermostat has become partially jammed.

Q: What does it mean when your temperature gauge stays on cold?

Normally, your temperature gauge will remain on the cold setting until your engine has had enough time to warm up. After then, it begins to gradually ascend. If the temperature gauge on your automobile is stuck in the chilly setting, it might be because the gauge is malfunctioning or because the thermostat has failed. If the thermostat constantly discharges coolant into the engine, the engine will get overheated, which will have an impact on the vehicle’s fuel efficiency and performance.

Q: Where should your temperature gauge be on your car?

On the temperature gauge, there are often indications for hot and cold temperatures. Additionally, if you pay close attention, you will see a marking in the centre. The average temperature for your automobile is indicated by the center marker. Following the start of your car’s engine, the needle on the temperature gauge begins to gently move.

If your automobile is operating normally over a lengthy distance, the car gauge will remain near the center of the dial. In an ideal situation, the temperature of your car should be between 195 and 220 degrees, which is around the midway marker on the temperature gauge.

Final words

It’s possible that your car’s temperature gauge is behaving strangely, fluctuating wildly. The most common causes of this inconsistency include a damaged radiator, a faulty water pump, a leak in the coolant level, and a faulty thermostat, among others. In addition, a burst head gasket might be a major contributing factor. If you observe that the temperature of your automobile fluctuates between high and low, you must repair any damaged components as soon as possible to prevent additional damage to the engine.

Leave a Comment

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