Diagnostic Aids

DTC P0125 set indicates a faulty ECT sensor. Comparing the engine coolant temperature displayed on a TECH 2 with actual coolant temperature measured with a thermometer may isolate this condition. If the displayed engine coolant temperature is not close to the actual coolant temperature, replace the ECT sensor.

Check for the following conditions:

• Poor connection at PCM: inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection.
• Damaged harness: inspect the wiring harness for damage. If the harness appears to be okay, observe the display on the TECH 2 while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the last set.