Toyota 3.0 Coolant Temp Sensor Location? 97 Most Correct Answers

Your car’s cooling fan or radiator fan plays an important role in keeping your engine cool. If it stops working, your engine could overheat and get damaged.

Here’s how to tell if your fan isn’t working, what to do about it, and what the problem might be.

How does a car fan work?

While driving, air flows through the car radiator to keep your engine at normal temperature. But when you’re stopped in a traffic jam, for example, your engine has to use an electric cooling fan to force air through the radiator.

The fan is temperature controlled to ensure the engine gets enough cool air to avoid overheating.

How do I know if the fan is not working?

Many modern cars don’t have a temperature gauge, but a light will indicate if the engine is overheating.

If you see a red or yellow temperature icon on your dashboard, you should stop as soon as it is safe to do so. A warning message may also appear on the dashboard display.

A yellow light likely means the coolant level is low. A red light means your engine is overheating.

What happens if the fan stops working?

If your cooling fan stops working, your engine could overheat. This could cause damage to your engine parts.

It is a serious problem and needs to be investigated by a workshop.

What should I do if my fan breaks?

When the red or yellow temperature light comes on, you must:

Stop as soon as it is safe.

Turn off the engine.

Have your car checked by a workshop or contact us.

In modern cars, it is difficult to check the fan yourself, because often you cannot see it. And when it stops working, you need a professional to fix it for you.

It is therefore best to take your car to a workshop. You can call us if your car won’t start or you think the engine is overheating.

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What’s wrong with my fan?

Your mechanic will look for any of these common fan faults:

Blown fuse

Since the radiator fan is electric, the problem could be with the fuse.

Your car’s manual should tell you where the fuse for the cooling system is located. If the fuse has blown, the mechanic must replace it immediately.

Faulty temperature sensor

On most modern cars, the fan is controlled by the Engine Control Unit (ECU), which receives a signal from the coolant temperature sensor.

If it doesn’t work, the fan won’t turn on when it needs to, meaning the motor could overheat.

Fan relay defective

The fan relay controls the power supply to the cooling fan. If there is a problem with the relay, the fan is affected.

This can cause the fan to cycle on and off or not turn on at all.

A wiring problem

Faulty wiring could be to blame. The mechanic will check that all wiring to the fan is properly connected and functional.

Something is wrong with the fan motor

If the motor that drives the fan is defective, a new motor must be installed.

Low coolant level

Check the engine coolant level. If your engine coolant is low, it means the cooling fan has to work harder to keep the engine at normal temperature.

To check the level, locate the coolant expansion tank in the engine compartment. There are usually two marks on it – a minimum and a maximum mark. The coolant level should always be between these 2 marks.

Find out how breakdown protection can help you in the event of car damage:

Published: July 13, 2017 | Updated: April 15, 2020 | Author: The AA

Your vehicle’s temperature sensor is an important component of your engine’s cooling system. So if you are having problems with your car or truck overheating, you may have a faulty sensor. Luckily, replacing a temperature sensor is as easy as plugging in a new one. However, you should test your sensor first to make sure the problem is there and you don’t have a deeper problem that needs fixing. With your handy multimeter, you can easily take a few measurements that will tell you if your sensor is working properly.

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More than we care to admit, a well-functioning temperature gauge is critical to our vehicle’s performance. Whether you have a turbocharged, fuel-injected wheeler or an older model, keeping engine temperature under control is imperative. Failure to do so will result in adverse effects including engine overheating, stalling and permanent engine damage.

There are several ways to spot a temperature gauge that has gone wrong. By feel and thorough inspection, you should be able to determine if symptoms such as incorrect temperature readings, unusual vibration, poor idling, and non-functioning cooling fans indicate a faulty gauge or other engine component.

Understandably, some of these indicators can overlap with more complex engine problems. To make a distinction between the two, here are the nine most common ways to tell if a temperature gauge is bad:

Erratic Temperature Gauge Readings Extreme Polarities Illuminated Check Engine Light Increased Fuel Consumption Starting Problems Cooling Fans Not Working Engine Overheating Black Smoke Other Performance Deficiencies

It may not be easy to determine the causes of your temperature gauge’s strange behavior. But if you can spot its symptoms, you’re already halfway to solving the problem.

Signs of a faulty temperature reading

1. Erratic readings from the temperature gauge

The most obvious sign that you have a bad transmission temperature gauge is an erroneous temperature reading. For example, you may find that your temperature gauge is increasing, but your car is not overheating. Likewise, it can simply stay on “cold” in the middle or go straight to high. These anomalies can be attributed to several factors, including a bad water pump or a faulty temperature sensor.

Based on reported incidents from vehicle owners, the four most common reasons for high temperature readings without overheating are as follows:

A bad water pump that doesn’t circulate the coolant through the engine

Faulty temperature sensor caused by dirt or debris

Corrupted temperature gauge incorrectly showing the actual coolant temperature

Clogged radiator due to age or poor quality

It is important to note that this incident should not be automatically blamed on faulty components. In this scenario, one of two things could happen – either the engine is wrong but the temperature gauge is off the charts, or the engine has exceeded its normal operating temperature but hasn’t reached the point where the PCM/ECM would consider it as evaluate overheating.

In any case, you need to check everything related to the engine, which directly or indirectly affects the air-fuel mixture and the cooling system of your vehicle. This is how you can approach one of these triggers.

2. Extreme polarities

This symptom is probably the second most common indicator of a faulty temperature gauge. And by that description I mean that the temp gauge can either be too hot or too cold, but it doesn’t match the engine temp.

The best way to do this is to read the actual temperature of your vehicle’s engine and compare it to the temperature gauge. Assuming you’ve determined that your engine is fine, the mismatched reading indicates one of the following potential problems:

Temperature sensor or transmitter unit defective

Faulty circuit in temperature gauge

Faulty wiring

Contaminated coolant system

Damaged thermostat

Corroded sensor, temperature gauge and ECU sensors

Defective temperature display

Defective control unit

3. Illuminated check engine light

As a universal indicator of trouble, your Check Engine Light going out means a multitude of things – including a possible fault with your temperature gauge. The CEL and temperature gauge warning lights will activate at the same time in most cases. Even if it isn’t, an activated Check Engine Light is a call to perform an immediate inspection of your vehicle, preferably with a highly specialized OBD-II or DBM-III scanner such as a Foxwell NT809 bi-directional scan tool (see Amazon ).

4. Increased fuel consumption

A faulty car temperature gauge indicates that you have bad coolant temperature or ECT sensors. Experienced car owners know all too well that faulty ECT sensors send incorrect signals to a vehicle’s PCM, or on-board computer. This leads to an incorrect air-fuel mixture and consequent misuse of fuel, which translates into poor fuel economy.

5. Startup problems

Since a temperature gauge’s function is largely related to the air/fuel mixture, an erroneous reading can cause difficulty starting your car. In worse situations, you may even have to live with a ban from starting. Compared to the other symptoms in this guide, this predicament has a broader scope – meaning you need to look beyond your temperature gauge and other potential triggers of your starting problems.

6. Non-working fans

Some cars with longitudinal or transverse engines use an electric cooling fan for their cooling system. And that’s an important fact to know about your vehicle. I say that because electric fans use a DC motor that is turned on or off with a thermal switch, module, or computer control – levers that are largely dependent on coolant temperature.

As previously stated, a bad temp gauge = a bad ECT sensor = improper air/fuel mixture. Ultimately, the faulty air-fuel mixture causes the electric fan to work intermittently or not at all. Although highly unlikely, it’s also possible that your fan could fail sooner than your temperature gauge. In this scenario, the former becomes the telltale sign pointing to the latter.

7. Engine overheating

When your vehicle’s cooling fan fails, engine overheating becomes inevitable. By this point, the signals sent to the on-board computer would already be distorted (not to say wrong) – resulting in an erroneous air-fuel mixture, which aggravates the situation. The above situation may not necessarily be the case for vehicles that use a separate ECT sensor for the cooling fan. But for those sharing the same sensor, owners could try fixing the temperature gauge next to this component.

8. Black smoke

Unlike the other items on this list, black smoke from your car’s exhaust is more of an indication than a symptom of a bad temperature gauge. When a faulty temperature gauge is detected but not fixed, this is one of the signs your vehicle is likely to show. Of course, black smoke can also be the result of your fuel mixture being too rich. But then again, that only happens when your temp gauge is faulty and sending incorrect signals to the PCM/ECM.

9. Other performance quirks

An erroneous temperature reading is typically accompanied by unusual vehicle behavior such as juddering at low speeds or loss of power. The best explanation is that a temperature gauge shows whether or not a car has the correct air-fuel mixture. Any disturbance in the air-fuel mixture is guaranteed to cause gauge malfunctions and performance problems. Mechanics and car enthusiasts cannot stress enough how crucial the air/fuel mixture is to vehicle performance.

How to diagnose a faulty temperature gauge

Although some of the symptoms associated with a bad temperature gauge are easy to spot, it can be difficult to pinpoint the problem to a specific one. As a vehicle owner, you have to do a lot of tinkering before you can come up with a forecast. A visit to the local mechanic may be unavoidable in the long run. But until then, here are some steps to help you determine if your temperature gauge is faulty or your engine is overheating:

1. Reach operating temperature

Run your grinder for about 20 minutes to bring it up to operating temperature (or until the temperature gauge shows it’s running hot).

2. Check your coolant tank

Next, open the hood and visually inspect your coolant tank. After running your engine for the specified time, your coolant level should be at the top line or mark that reads full/hot. If it doesn’t, you could be running out of coolant or have a potential coolant leak.

3. Check the color of the coolant

Also note the color of the coolant. It should be a translucent green or orange depending on its original color when you first added it. If it appears cloudy, rusty, or muddy in the slightest, the coolant could be contaminated (which would explain why your engine is running hot).

4. Check the radiator cap

After that, allow your engine to cool and check to see if the radiator cap is loose, as this contributes to inconsistent temperature signals.

5. Check the radiator hose and engine head

While doing this, check the radiator hose and the engine head (near the thermostat) – they should be hot to the touch. If not, it could be a clogged radiator or a faulty water pump.

6. Confirm that the fan is running

Make sure your fan is running. Typically, a cooling fan activates at 110°C (230°F). A non-working fan would mean your engine is overheating.

7. Check the radiator hose and engine

To test if you have a stuck thermostat, check if your radiator hose and engine are warm.

8. Compare temperatures

Compare the temperature of your lower and upper radiator hoses. Under normal circumstances, the lower hose should be cooler than the upper. You can consider coolant circulation problems or a potential coolant leak if this condition is not met.

I wouldn’t wish for it, but you should be able to uncover more triggers by doing these procedures. But if all of these steps and components are checked while your temp gauge is still behaving strangely, chances are your temp gauge is the culprit.

Word to the wise:

A coolant temperature sensor (CTS, ECT or ECTS) measures the temperature of the coolant/antifreeze mixture in your vehicle’s cooling system and ultimately controls your temperature gauge. So if the latter malfunctions or goes haywire, chances are there’s something wrong with your coolant temperature sensor as well.

How much does a temperature gauge repair cost?

Ultimately, this will dictate your spending, causing your temperature readings to fluctuate and the temperature reading to go bad. Potential repairs and associated costs are different for each item we’ve covered in this guide. Depending on the reason you uncover, the non-exhaustive table below should give you a good idea of ​​the costs:

Component Estimated Cost Coolant $20-100 Other defective sensors $100-300 Temperature Gauge $150-300 Temperature Sensor or Transmitter Unit $150-375 ECT Sensor $150-430 Thermostat $200-350 Radiator $150-1200 Water Pump $720-1820 Head Gasket $715 – $2,000 PCM, ECM or ECU $800 – $2,000

Conclusion – How to tell if the temperature gauge is bad

To recap, here are the nine most common signs of a bad temperature gauge, discussed in today’s article:

Erratic Temperature Gauge Readings Extreme Polarities Illuminated Check Engine Light Increased Fuel Consumption Starting Problems Cooling Fans Not Working Engine Overheating Black Smoke Other Performance Deficiencies

I hope you find this guide useful as driving around with a broken temp gauge is never a good idea. I highly recommend addressing the issue urgently as soon as you notice any of these symptoms. This saves you from not being able to use your car’s defroster or heating system (a big bonus when driving in cold or inclement weather). Most importantly, you avoid unnecessary repair costs – not to mention permanent damage to your car engine and its components.

There is none per se. There will be a fused wire with voltage to the instrument cluster (your owner’s manual should specify which fuse), but the temp sensor provides a variable “resistance to ground” that mirrors the temp gauge in the dash. A cold engine will have a high resistance across the sensor, and a hot engine will have a lower resistance. For this reason the temperature sensor is specific to the temperature range and temperature gauge in your vehicle. A Vermin-Club certified technician can check the electrical wiring and replace a fuse for you if you need further assistance.

The coolant temperature sensor is responsible for monitoring the coolant temperature in your car engine.

It is necessary to monitor the engine coolant because the engine requires more fuel when the engine is cold and less when the engine is warm.

When measuring the coolant temperature, the sensor sends a signal to the car’s computer. This signal is then used to adjust both engine timing and fuel injection. This enables optimal engine performance.

If the computer detects that the engine is overheating, it adjusts the power settings to prevent overheating.

Faulty coolant temperature sensor – 4 common symptoms

It is important to know that a failure of your car’s coolant temperature sensor can damage your car engine. Do not ignore the following signs –

Fuel consumption increases

One of the very first signs that you may have a faulty coolant temperature sensor is when you notice a drop in your fuel economy. The reason for this is as follows:

The faulty sensor may be sending an incorrect signal to the computer, causing engine timing and fuel calculations to miscalculate.

If the computer continues to receive a cold signal from the faulty sensor, it will interpret this as if the engine is cold and will continue to inject fuel.

Not only does this action result in poor fuel economy, but more importantly, it can affect engine performance.

Check if the engine light is flashing

If your check engine light starts blinking, it could also indicate a faulty coolant temperature sensor. Any time this warning light comes on, we advise car owners to have it checked immediately to avoid possible engine problems.

If you cannot identify what is causing the “Check Engine Light” warning, see a professional mechanic as soon as possible.

Engine overheating

When the coolant temperature sensor is not working, it can cause your car engine to overheat. While sometimes a faulty sensor will send a permanent cold signal to the engine, it can also send a permanent hot signal.

The computer will again miscalculate the signal and cause the motor to heat up instead of cooling down. When this happens, the car may misfire or cause engine knock.

Black smoke from the exhaust

Black smoke coming out of your car’s exhaust could be another indication that your car’s coolant temperature sensor is faulty or failing. Here’s what happens:

Erroneous readings from the coolant temperature sensor can cause the engine to miscalculate the air/fuel mixture in the engine.

Whenever the air-fuel mixture ratio is out of proportion and the fuel mixture becomes too rich, the fuel cannot burn in the combustion chamber.

As a result, the fuel burns in the car’s exhaust pipes, causing the exhaust to release black smoke.

If the amount of black smoke coming from a car is excessive, it is best not to attempt to drive the car.

If you notice this with your car, have your car checked by a professional as soon as possible.

Don’t ignore the warning signs

The coolant temperature sensor is a crucial component in ensuring your engine is operating at its optimum level. Based on the signals from the sensor, the car computer calculates the engine timing and fuel injection. If the signal is wrong, this important calculation will be misjudged.

If you notice any of the above signs, have your car checked immediately to avoid possible engine problems.

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If you suspect a coolant temperature sensor problem, visit us at Virginia Auto Service for quick diagnosis and resolution of the problem. If you need another auto repair service or even need routine maintenance, we can help.

Call us today at 602-266-0200 or schedule a visit with us online.

They checked everything from the starter, the alternator, the fuel pump, if the crankshaft sensor is cut out so the car won’t start. The temperature sensor does not allow the car to start

My car has 149,000 miles.

My car has an automatic transmission.

Every driver knows that coolant/antifreeze is needed to keep an engine at its optimum temperature. But how do cooling systems know when the engine is at the right temperature?

In this guide, we’ll take a closer look at coolant temperature sensors, providing information on what they do and how they work, as well as step-by-step instructions on how to diagnose and replace a faulty sensor.

What is a coolant temperature sensor and how does it work?

A coolant temperature (CTS) sensor (also known as an ECT sensor or ECTS (engine coolant temperature sensor) is used to measure the temperature of the coolant/antifreeze mixture in the cooling system and provides an indication of how much heat the engine is giving off. The sensor works with the ECU of the vehicle and continuously monitors the coolant temperature to ensure the engine is running at the optimum temperature.

To get an accurate reading of the current engine temperature, the ECU sends a regulated voltage to the CTS. The resistance of the sensor varies with temperature, allowing the controller to monitor changes in temperature. The ECU uses this reading to calculate coolant temperature and from there adjusts fuel injection, fuel mixture, ignition timing and controls when the electric cooling fan turns on and off. This information is also used to send an accurate reading of engine temperature to a gauge on the dashboard.

How to identify a faulty coolant temperature sensor

Like any under-the-hood component, coolant temperature sensors can develop errors over time. A faulty sensor can lead to a number of problems including overheating and poor engine performance. Because of this, it’s important to know how to spot the signs of a faulty or failed temperature sensor before it can cause further problems that could be more expensive to fix.

Start by looking at the device itself to check its condition as sensors/seals/connectors can crack with prolonged use and constant temperature changes. The CTS is usually located at the front of the car, near the thermostat housing or on the radiator. While a visual inspection can help diagnose some faults, not all problems with a CTS will present visible symptoms.

Below we list the other signs and symptoms that could indicate a CTS problem:

Erratic reading on dashboard gauge (should be 88-90°C when engine is warmed up)

Engine overheating (highlighted by dash gauge)

Check Engine Light warning on dashboard

Rough engine noise at idle

Limited power (caused by ECU miscalculating fuel rich mixture)

Bad fuel consumption

If you are in doubt as to which component under the hood is faulty, take your car to a professional mechanic for a full diagnosis.

How to replace a coolant temperature sensor

Replacing a coolant temperature sensor is an easy process for anyone familiar with an engine’s components and can be performed right on your powertrain. The following steps show how to replace a faulty coolant temperature sensor in your car.

Step 1: Locate the sensor

The CTS is usually located at the front of the engine, near the radiator or thermostat housing. Since it’s a small component, often found further down the engine bay, you may need to use a light or flashlight to locate it. Removing the engine cover can also help you locate it if it is near the thermostat housing.

Step 2: Remove the connection cable from the terminal

The CTS is connected to the ECU via a connector that you must unclip and remove. Do this with care as the plastic connector and wiring can often be brittle and if broken will require a complete replacement. Unplug the connector and set the cord aside out of the way.

Step 3: Unthread and remove the old sensor

Coolant sensors are built in like a spark plug, so you have to unscrew them to remove them. Using a deep socket wrench and ratchet, carefully loosen the sensor counterclockwise without applying too much pressure. A spritz of release spray can help loosen stuck sensors. Once the sensor is loose, unscrew it by hand and remove it from the socket. At this point, coolant is likely to be leaking, so have the new one on hand to replace, or consider draining the coolant if necessary.

Step 4: Install the new sensor

Use a rag or cloth to clean the area of ​​dust and debris that may affect the performance of the new CTS. Insert the new sensor into the threads and turn clockwise by hand. Make sure that the sensor sits well in the socket. Then use a torque wrench to tighten the sensor to the value specified in the manufacturer’s instructions.

Step 5: Plug the connection cable back in

Once the new sensor is in place, all that remains is to reconnect the cable. Make sure the connector is clean and free of debris, then carefully insert it into the new sensor, gently tightening all clips to ensure a good connection with the connector. To ensure the new sensor is working, start the engine and while it warms up watch the temperature gauge on the dash to ensure the correct temperature is being maintained.

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The coolant temperature sensor is used to measure the engine coolant temperature. The readings from this sensor are then reported back to the engine control unit (ECU). This data from the sensor is then used to adjust fuel injection and ignition timing. On some vehicles, the sensor can also be used to turn on the electronic cooling fans. The data may also be used to provide readings for a dash coolant temperature gauge.

The ambient air temperature sensor is used to measure the temperature of the air outside the vehicle. It is often located behind the front bumper, but on some vehicles it can be found behind the glass in the wing mirror. It is used to estimate air density and by air conditioning – the system will not work if the air is too cold outside.

The average price to replace an engine temperature sensor is between $150 and $193. Labor costs range from $82 to $105, while parts range from $66 to $88. Taxes and fees are not included in the estimate.

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P0128 code definition

Coolant thermostat (coolant temperature below the control temperature of the thermostat)

What the P0128 code means

The P0128 code means the engine coolant is not getting warm enough quickly enough. In other words, there is a problem that the engine operating temperature is not reached within a certain time. The engine control module (ECM) determines this amount of time based on the ambient temperature.

What causes the P0128 code?

There are two main causes of P0128:

The most common cause is an engine coolant thermostat that stays open or opens prematurely. The next cause is a problem with the engine coolant temperature sensor or the wiring connected to the sensor.

What are the symptoms of the P0128 code?

The heater does not get hot enough because the coolant temperature in the engine is too low

The car takes too long to warm up or the temperature gauge doesn’t rise as high as it used to

How does a mechanic diagnose the P0128 code?

Diagnostic methods can vary from mechanic to mechanic, but the first thing I check is to see what the coolant temperature is when coolant starts flowing through the radiator hose connected to the thermostat.

In general, the hose should barely be warm before the thermostat opens. When the thermostat opens, very hot coolant should begin to flow and rapidly heat the radiator hose. You have to be careful because it is so hot that you could burn yourself.

If the radiator hose heats up slowly and does not suddenly become hot, the cause is a stuck open thermostat. If the hose suddenly gets as hot as it should, then the next thing to check is the reading you are getting from the coolant temperature sensor.

You’ll need a scan tool to do this accurately, but a reading is also possible if your car has a temperature gauge. You need to compare this reading with an infrared thermometer. The temperature of the thermometer should normally be around 200 degrees Fahrenheit. If the scanner reading does not exactly match the thermometer reading, there is a problem with the sensor side of the vehicle.

When this is the case, the connectors are usually degrading and causing a bad connection. If the plug is OK, then the sensor is usually to blame.

In very rare cases there may be a problem with the supply voltage supplied by the Engine Control Module. I won’t go into detail on this as you will need factory level information which will vary from car to car and you will need a good knowledge of electronic diagnostics to avoid damage to the vehicle.

Common mistakes made when diagnosing the P0128 code

Replacing the thermostat without checking the vehicle:

If you ask a mechanic for a P0128 code, at least 9 out of 10 people are sure to tell you that the thermostat is to blame. The vast majority of the time they would be right. However, every once in a while it is possible for the thermostat not to fix this code.

How Serious is the P0128 Code?

P0128 is not a very serious code. However, if it is not repaired and the vehicle is used for a long period of time, there is a small possibility that water contamination of the oil can lead to deterioration and engine failure. Since this code is set when the coolant is not getting hot enough, it means the engine is not getting hot enough for the condensation in the engine to be burned off; that water could get into the oil. Any resulting engine failure would most likely last for years, but the chance is there.

What repairs can fix the P0128 code?

Replacing the thermostat (most common repair)

Replacing the coolant temperature sensor or the wiring and connector associated with the damaged sensor

Normally this code is only displayed during the cold winter months.

During the warmer months, ambient temperatures help the vehicle warm up normally, while cold weather makes it difficult for the engine to warm up.

Need help with a P0128 code?

Vermin Club offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Request a quote online, book an appointment, or speak to a service advisor at 1-800-701-6230.

Check the engine light

P0128

error codes

They checked everything from the starter, the alternator, the fuel pump, if the crankshaft sensor is cut out so the car won’t start. The temperature sensor does not allow the car to start

My car has 149,000 miles.

My car has an automatic transmission.