Engine Temperature Sensor: Testing and Inspection

A "Scan tool" displays engine temperature in degrees centigrade. After engine is started, the temperature should rise steadily to about 90°C then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature (ECT) and intake air temperature (IAT) readings should be close to each other. A fault in the ECT sensor circuit should set a diagnostic trouble code (DTC) 14. Specifications also contain a chart to check for sensor resistance values relative to temperature.