Component Testing

Engine Coolant Temperature Sensor Circuit:

Coolant Temperature Sensor Test:

1. Remove the Coolant Temperature Sensor.
2. With the sensing portion of the Coolant Temperature Sensor immersed in hot water, check for continuity between the two terminals. The sensor should be held with its threaded housing 3 mm (1/8 in) away from the surface of the hot water.
Standard Values
Continuity at 180-190° F
No continuity at 172° F or less

3. If the continuity deviates from the standard value, replace the sensor.

Note: If the temperature of the engine coolant is known, then the sensor may be tested at the connector, without removing it from the thermostat housing.


If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, clear the trouble codes and road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.

If the same trouble code reoccurs, it is possible that there is an intermittent failure of the component or the ECM. Check for looseness at all harness junctions and test for an intermittent failure.