Test Description
The numbers below refer to the step numbers in the diagnostic table.
- 5: This step tests for excessive resistance in the ECT circuit.
- 6: This step isolates the condition. If the temperature changes, test for a condition in the low reference circuit. If the temperature remains the same test the signal circuit for a condition.
DTC P0125
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | - | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Is the engine cooling system low on coolant? | - | Go to Loss of Coolant (LH2 and LY7) or Loss of Coolant (LC3) | Go to Step 3 |
| 3 | Is the customer's concern that the engine does not reach operating temperature or that the heater output is low? | - | Go to Thermostat Diagnosis | Go to Step 4 |
| 4 |
IMPORTANT:
Return to this diagnostic procedure after you complete the thermostat diagnosis. Test for the correct operation of the thermostat. Refer to Thermostat Diagnosis
.Did you find and correct the condition? |
- | Go to Step 13 | Go to Step 5 |
| 5 |
|
139°C (282°F) | Go to Step 9 | Go to Step 6 |
| 6 |
|
139°C (282°F) | Go to Step 7 | Go to Step 8 |
| 7 | Test the low reference circuit of the ECT sensor for high resistance. Refer to Circuit Testing
and Wiring Repairs
. Did you find and correct the condition? |
- | Go to Step 13 | Go to Step 10 |
| 8 | Test the signal circuit of the ECT sensor for high resistance. Refer to Circuit Testing
and Wiring Repairs
. Did you find and correct the condition? |
- | Go to Step 13 | Go to Step 10 |
| 9 | Test for shorted terminals and poor connections at the ECT sensor. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
- | Go to Step 13 | Go to Step 11 |
| 10 | Test for shorted terminals and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
- | Go to Step 13 | Go to Step 12 |
| 11 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement
. Did you complete the replacement? |
- | Go to Step 13 | - |
| 12 | Replace the ECM. Refer to Control Module References
for replacement, setup, and programming. Did you complete the replacement? |
- | Go to Step 13 | - |
| 13 |
|
- | Go to Step 2 | Go to Step 14 |
| 14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK |