P0125

Circuit Description
The Control Module (PCM/VCM) monitors the (ECT) sensor and Engine Run Time in order to determine how long it lakes the ECT to reach the coolant temperature required for Closed Loop operation. DTC P0125 sets if the Control Module determines that the ECT does not reach a minimum coolant temperature required for closed loop operation in a specified amount of time.

Conditions for Running the DTC
^ The engine is running
^ No active ECT sensor DTCs
^ No active IAT sensor DTCs
^ The IAT is more than -40°C (-40°F)
^ The ECT is more than -40°C (-40°F)
^ The start-up ECT is 40°C (104°F) or less

Closed Loop Test
^ Vehicle stabilized at -40°C (-40°F)
- Accumulated air flow since start is more than 7500 grams
- Accumulated idle time is less than 360 seconds
^ Vehicle stabilized at -7°C (20°F)
- Accumulated air flow since start is more than 4500 grams
- Accumulated idle time is less than 225 seconds
^ Vehicle stabilized at 10°C (50°F)
- Accumulated air flow since start is more than 1600 grams
- Accumulated idle time is less than 90 seconds

Conditions for Setting the DTC
^ The closed loop coolant temperature is not reached within a predetermined time. The maximum allowable time depends on the start-up coolant temperature and the amount of air flow into the engine.
^ Vehicle stabilized at -40°C (-40°F)
ECT less than 20°C after 8 minutes (68°F)
^ Vehicle stabilized at -7°C (20°F)
ECT less than 20°C after 5 minutes (68°F)
^ Vehicle stabilized at 10°C (50°F)
ECT less than 20°C after 2 minutes (68°F)

Action Taken When the DTC Sets
^ The Control Module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
^ The Control Module will set the DTC and records the operating conditions at the time the diagnostic fails. The Control Module stores the failure information in the scan tools Freeze Frame and/or the Failure Records.

Conditions for Clearing the MIL/DTC
^ The Control Module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the Engine Coolant Temperature is more than 70°C (158°F) during the same ignition cycle).
^ Use the scan tool Clear Information function.

Diagnostic Aids
When a DTC P0125 sets, an out of range ECT sensor or an engine thermostat that does not operate correctly is indicated.

Check for a poor connection or a damaged harness. Inspect the VCM harness connector for the following conditions:

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This test checks the engine warm-up rate. In the Conditions for Setting the DTC text, the technician should be able to reference the allowable engine run time relative to the cold start up temperature of the vehicle.
4. This test checks the coolant sensor reading on the scan tool and the actual coolant temperature.