Diagnostic Aids
- Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to TEMPERATURE VERSUS RESISTANCE - ENGINE COOLANT TEMPERATURE SENSOR .
- If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3 °C (5 °F).
- After starting a cold engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens.
- High resistance on either the ECT sensor signal circuit or the ECT sensor low reference circuit could set a DTC.