The ECT sensor is a two-pin temperature sensor that supplies the coolant temperature to the ECM and the instrument cluster. It works in a similar way to an NTC (negative temperature coefficient) sensor; its resistance drops as the temperature of the coolant increases. The ECM changes ignition timing and air/fuel mixture with regard to the water temp; the sensor receives a 5-volt reference voltage, the voltage drop across the sensor varying with water temperature. If ECT sensor input is out of range, or unrealistic expected by the ECM, the MIL comes on whenever the OBD II fault criteria is met, and to ensure the engine runs, the ECM sets an assumed ECT value at 80 degree Celsius plus its offset 176 degrees f, while setting ignition timing to a conservative basic setting. It is mounted at the rear of the engine, to the left of cylinder 6, beneath the intake port and above the
Intake Manifold. It is located under the intake manifold and thus to get to it, the manifold must be taken off after the engine has cooled. The ECT sensor connector has to be removed to eliminate the connection, and the sensor should then be unscrewed from the cylinder head, be careful as there will be some lose coolant. For reinstallation a new copper sealing washer has to be used, lost coolant has to be replenished and the DTC had to be checked and then cleared of its memory by resetting the ECM.