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  • The engine coolant temperature sensor (CTS) sits near the thermostat housing on most vehicles.
  • Some engines have a cylinder head temp sensor that does the job of the CTS and the cylinder head temperature (CHT) sensor.
  • The CTS sends engine temperature information to the powertrain control module (PCM) for setting spark timing, fuel mixture, idle air control position, and other processes.
  • You can access the CTS by removing the pressure cap, draining the cooling system, and pushing or lifting the safety clip that keeps the sensor attached.

Q: Where Is the coolant temperature sensor (CTS) Typically Located?

A: There are, on some engines, two engine temperature sensors. The engine coolant temperature sensor (CTS) is located near the thermostat housing on most vehicles. The cylinder head temperature sensor (CHT) is located on the side of the head that is farthest from the exhaust. But the cylinder head temp sensor serves both purposes on some engines, and it’s subject to be found in various places on one or the other cylinder head.

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image showing the cylinder head temp sensor locations
Illustrations showing various locations of the cylinder head temperature sensor. | Image Source: Richard McCuistian

Caution: To prevent serious burns, never open a hot cooling system.

The CTS sends engine temperature information to the powertrain control module (PCM) for proper spark timing and fuel mixture. The PCM also uses CTS readings for idle air control position, O2 sensor closed-loop status, canister purge on/off times, and idle speed.

A CTS with a poor connection at the wiring connector will cause the PCM to supply an overly rich fuel mixture. Meanwhile, a shorted CTS or one that has a low resistance will cause the PCM to supply an overly lean fuel mixture, resulting in drivability issues.

Tips on How to Access the CTS

There are a few things you should inspect before tinkering with the coolant temperature sensor.

Make sure that the cooling system is properly filled, the radiator has the right amount of pressure, there is a proper water-antifreeze mixture, and the cooling fan is operating as it should.

After inspecting all of these, you can proceed with removing the CTS.

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Protective eyewear and gloves are essential when removing the CTS. To begin, remove the pressure cap to relieve the system of residual pressure and drain the cooling system to access the sensor.

A safety clip is typically used to keep the sensor in place, and you only need to push or lift it to release the sensor. After removing the sensor, check the electrical terminal for signs of corrosion. You might need to replace the sensor pigtail if it’s corroded.

About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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Robert Morris

Great to see Car Parts put this information on their website. I’d venture that 90% of owners (especially women) don’t know very much about the details you have addressed. It would be great if you put those details with some pictures in a small pamphlet, so it would fit in a glove box. AAA, and similar programs, and driver education could use these for new drivers etc.

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