Engine Coolant Temperature Sensor

Engine Coolant Temperature Sensor

The engine coolant temperature (ECT) sensor transmits a signal to the engine control module (ECM) describing the temperature of the engine coolant. This gives the ECT sensor a measurement of engine temperature and influences the control of:
- Injection period
- Idling speed
- Engine coolant fan (FC)
- Ignition timing
- On-board diagnostic (OBD) functions.

The sensor incorporates a temperature-sensitive resistance with a negative temperature coefficient (NTC). The sensor is supplied with a stabilized voltage of 5 V from ECM.

The voltage across the sensor is a function of engine temperature and, therefore, of sensor resistance. Voltage can be between 0 V and 5 V.

The ECM uses substitute values if the signal from the ECT sensor is missing or faulty, however, substitute values can cause starting problems in very cold weather.

The sensor is mounted in the thermostat housing.