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

Engine Coolant Temperature (ECT) Sensor:

The Engine Coolant Temperature (ECT) sensor constantly supplies the Electronic Control Assembly (ECA) with a signal reflecting engine coolant temperature. The ECT is a negative temperature coefficient sensor, meaning that as the temperature of the sensor increases, the resistance will decrease. The ECA reads the varying sensor resistance and determines the engine operating temperature, using this information to optimize the air/fuel mixture, idle speed, fuel pressure, purge flow, and EGR flow. On turbocharged engines the ECT signal also modifies injector timing, ignition timing, and boost pressure.