Engine Coolant Temperature Sensor

The engine coolant temperature (ECT) sensor supplies the engine control module (ECM) with a signal describing coolant temperature. This gives the engine coolant temperature sensor a measurement of engine temperature and influences the control of:

^ injection period
^ idling speed
^ engine cooling 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 Volts from the engine control module.

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

The engine control module uses substitute values if the signal from the engine coolant temperature sensor is missing or faulty, however, substitute values can cause starting problems in very cold weather.

The engine coolant temperature sensor is located in the thermostat housing.