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. A fault in the engine coolant sensor circuit should set DTC P0117 or DTC P0118. The DTC tables also contain a table to check for sensor resistance values relative to temperature. Refer to DTC P0117 ECT Sensor Circuit Low Voltage or DTC P0118 ECT Sensor Circuit High Voltage. Refer to Diagnostic Trouble Code Tables.