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

Engine Coolant Temperature Sensor (ECT)





The ECT (engine coolant temperature) sensor is located at the front of the engine at the rear of the thermostat housing. The ECT (engine coolant temperature) sensor is a thermistor used to monitor the engine coolant temperature. The engine coolant temperature sensor is vital to the correct running of the engine as a richer mixture is required at lower block temperatures for good quality starts and smooth running, leaning off as the temperature rises to maintain emissions and performance.

The sensor has an operating temperature range of -40 Degrees Celsius to 120 Degrees Celsius. The maximum engine coolant temperature the ECM (engine control module) outputs on the CAN (controller area network) is the 120 Degrees Celsius. When a defective coolant sensor is detected, the ECM (engine control module) uses the oil temperature sensor value. Should both the oil temperature sensor and the coolant sensor fail the ECM (engine control module) defaults to 119 Degrees Celsius.