DTC P0125: Insufficient Coolant Temp. For Closed Loop Fuel Control
- Check thermostat operation. If heater takes a long time to become effective, or coolant flows into radiator on cold start, remove thermostat for inspection. Replace as necessary and retest system. If thermostat operates properly, go to next step.
- Drain coolant. Disconnect ECT sensor harness connector and remove sensor from engine. Measure resistance between ECT sensor terminals while immersed in a container of water. Heat water slowly and ensure resistance changes as specified. See ECT SENSOR RESISTANCE table. If resistance is not as specified, replace ECT sensor. If resistance is as specified, check for high circuit resistance. If wiring and connector are okay, replace PCM.
ECT SENSOR RESISTANCE
| Temperature °F (°C) | Ohms |
|---|---|
| 32 (0) | 5210-6370 |
| 68 (20) | 2210-2690 |
| 104 (40) | 1140 |
| 140 (60) | 580 |
| 176 (80) | 290-350 |