Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- Low engine coolant level - Engine Coolant Temperature (ECT) sensor harness is open or shorted - Engine Coolant Temperature (ECT) sensor electrical circuit poor connection - Faulty Engine Coolant Temperature (ECT) sensor - Faulty engine coolant thermostat

When Detected

Indicates the enging coolant temperature (ECT) or cylinder temperature (CHT) sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting the engine

Description

The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the Engine Control Module (ECM). The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.