How To Replace a Coolant Temperature Sensor | Autance

A coolant temperature sensor keeps your car running right.

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How To Replace a Coolant Temperature Sensor | Autance © How To Replace a Coolant Temperature Sensor | Autance

Dogs use panting to cool down, some birds use throat vibrations, humans use perspiration, and a car uses a mixture of water and antifreeze. That mixture is known as coolant, and it runs through a car’s engine to keep the car from overheating.

Regularly serviced and cared-for modern cars are highly unlikely to overheat due to a number of safety nets and precautions designed to avoid that exact situation. One such security layer is known as the coolant temperature sensor. To better understand your car’s cooling system, you must understand how the coolant temperature sensor works and what it does. The editors at Car Autance can do just that.

What Is a Coolant Temperature Sensor and What Does It Do?

A coolant temperature sensor (CTS) is a small device that reads the cooling system’s coolant temperature by measuring and responding to changes in electrical resistance. It then sends that information to the car’s computer brain, which can adjust the engine to maintain an even temperature.

Where Is the Coolant Temperature Sensor Located?

The coolant temperature sensor is most frequently located on the engine block or head near the thermostat or the coolant intake.

How Can I Check the Coolant Temperature Sensor?

Using a multimeter, check the current of the connectors and the resistance of the sensor.

What Are the Symptoms of a Failing Coolant Temperature Sensor?

If the coolant temperature sensor is not able to function, it could cause a reaction of numerous issues. The symptoms are not always directly related, but they could lead back to the CTS.

  • Check Engine Code

If the computer detects a signal failure from the CTS, it might throw a code that will be indicated on your dashboard with a check engine light.

  • Overheating

If the temperature sensor is not working, it will not be able to tell the car that the temperature of the coolant is rising and could overheat.

  • Temperature Gauge Spiking High or Low

If the coolant temperature sensor is bad, you might not know that the coolant is too hot or has drained. This could result in a range of engine temperature fluctuations, which will show on the dashboard.

  • Poor Fuel Economy

Without proper coolant temperature readings, the system might use more fuel, which results in lower fuel economy.

  • Coolant Leaking Around the Sensor

In some cases, maybe the seal is bad or the sensor was knocked, coolant might leak out.

  • Rough Start or Idle

The coolant temp sensor informs the ECU with information that affects the fuel and spark delivery within the engine. If the sensor is off, ignition and idle speed could be affected.

  • Emissions Issues

If the engine sprays too much fuel as a result of a faulty coolant temperature sensor, it might make its way through to the exhaust.

Common Causes of a Failing Coolant Temperature Sensor

Several things can happen to a coolant temperature that could cause it to malfunction.

  • Faulty wiring
  • Corroded, failing, or unplugged connector
  • Bad seal
  • Physically broken
  • Device failure

How To Replace a Coolant Temperature Sensor

1. Park Your Car on a Level Surface and Let it Cool

Use your service manual to locate the coolant temperature sensor. Some might be tucked away and you might have to remove other parts for access.

2. Drain the Coolant to a Level Where it’s Safe to Remove the CTS

This might not always be necessary, but flush the system if the coolant is contaminated.

3. Unplug the Coolant Temperature Sensor

Remove the coolant temperature sensor, and replace it by hand-tightening the new coolant temperature sensor into the block. Use a torque wrench to tighten the sensor. Plug in the new coolant temperature sensor connector.

4. Replace any Removed Parts and Add Coolant.

Replace discharged coolant. Bleed air out of the coolant system, if necessary. Button everything up, and you’re finished.

FAQs About Coolant Temperature Sensor

Car Autance answers your burning questions!

Q: Is a Coolant Temperature Sensor the Same as a Thermostat?

A: Whereas the coolant temperature sensor reads the coolant temperature, the thermostat regulates the flow of coolant into the engine to maintain its temperature.

Q: How Long Does a Coolant Temperature Sensor Last?

A: This will depend on numerous factors such as driving conditions, temperature and climate, as well as ownership and care. They aren’t designed to last forever, but it’s also not a super common service item.

Q: What Happens If You Unplug the Coolant Temperature Sensor?

A: If you unplug the coolant temperature sensor, you might experience the symptoms discussed above. A check engine code will almost certainly show up.


Car Autance’ editors understand that not everyone is a text-based learner. For those kinesthetic people out there, we have your back with a video showing you exactly how a coolant temperature sensor works. We pulled it from a trusted source, and it’s a great additional resource.

Car Autance’ Suggested Tools

Choosing tools from the overcrowded pool of options can be daunting and overwhelming, so we’ve picked one out for you. If you don’t have the necessary tools already, consider this Stanley Mechanic’s tool kit to help you along.

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