Where Is the CTS Located?

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.

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.

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.