Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

The scan tool displays engine coolant temperature in degrees. After engine start-up, the temperature should rise steadily to about 90°C (194°F) then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature and intake air temperature displays should be close to each other. When the PCM detects a malfunction in the Engine Coolant Temperature (ECT) sensor circuit, the following Diagnostic Trouble Code (DTC)s will set:

^ DTC P0117 circuit low.
^ DTC P0118 circuit high.
^ DTC P0125 excessive time to Closed Loop. The above DTCs contain a table to check for sensor resistance values relative to temperature.

Refer to Diagnostic Tables. Testing and Inspection