Scan Tool Testing

ENGINE COOLANT TEMPERATURE SENSOR
The Tech 1 scan tool (or equivalent) displays engine coolant temperature in degrees Celsius and Fahrenheit. After 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 been run for several hours (overnight), the Engine Coolant Temperature (ECT) and Intake Air Temperature (IAT) should be close to each other.

SENSOR CIRCUIT FAULTS
High Temperature Indicated
If the ECT sensor circuit indicates a high temperature, Diagnostic Trouble Code 14 Engine Coolant Temp Sensor (High Temp) will set. DTC 14

Low Temperature Indicated
If the ECT sensor circuit indicates a low temperature, Diagnostic Trouble Code 15 Engine Coolant Temp Sensor (Low Temp) will set. Powertrain Controls - ECM/PCM