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

A Tech 1 scan tool displays the engine temperature in degrees Celsius. After the engine is started, the temperature should rise steadily to about 90°C (194°F) then stabilize when the thermostat opens. If the engine has not run for several hours (overnight) the Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) temperatures should be close to each other. A fault in the ECT sensor circuit should set a Diagnostic Trouble Code (DTC) 14 ECT Sensor Circuit (High Temp) or DTC 15 ECT Sensor Circuit (Low Temp). The diagnostic trouble charts also contain a chart to check for sensor resistance values relative to temperature. Testing and Inspection