DTC Confirmation Test

NOTE: For best results, perform test with ambient temperature at 14°F (-10°C) or more and engine coolant temperature 14-140°F (-10-60°C).

Malfunction is detected when engine coolant temperature does not reach a specified temperature, even though engine has been running for a specified time. Possible causes are:

Stuck open thermostat.
Thermostat seal leaking.
Defective Engine Coolant Temperature (ECT) sensor.

To set DTC, replace thermostat using an OEM thermostat. Turn ignition on. Select DATA MONITOR with scan tool and observe engine coolant temperature. Ensure engine coolant temperature is less than 140°F (60°C). Drive vehicle at 50-75 MPH for 10 consecutive minutes.