Coolant Temperature Sensor/Switch (For Computer): Description and Operation

The Engine Coolant Temperature sensor (ECT sensor) has a thermistor which senses temperature changes. Thermistor resistance decreases as the temperature rises.

The ECT sensor detects the engine coolant temperature and provides this information to the Powertrain Control Module (PCM). If the ECT sensor malfunctions, the fan motor will operate at high speed as soon as the engine is started. The ECT sensor is located on the top of the water hose connection.