Engine Coolant Temperature (ECT) Sensor

ECT sensor is located on top of thermostat housing. Sensor is a thermistor type, which provides ECM with engine temperature information. ECM uses this information to control air/fuel mixture, ignition timing, idle speed, exhaust gas recirculation system and canister purge system.

To determine engine temperature, ECM supplies and monitors a voltage signal to coolant sensor. As engine temperature increases, sensor internal resistance decreases, causing ECM monitored voltage to decrease as more signal voltage passes through sensor to ground.