DTC P0115 Or P0125 - Engine Coolant Temperature (ECT) Sensor
- Check Power Supply
Turn ignition off. Disconnect ECT sensor harness connector. See Fig 1. Turn ignition on. Measure voltage between ECT sensor harness connector terminal "b" (Blue/Orange wire) and ground. See Fig 2. If voltage is approximately 5 volts, go to next step. If voltage is not 5 volts, verify harness continuity of Blue/Orange wire between ECT sensor and ECM. Repair harness or connectors as necessary. - Check Ground Circuit
Turn ignition off. Check ECT sensor harness continuity between terminal "a" (Black wire) and engine ground. See Fig 3. If continuity is present, go to next step. If continuity is not present, verify harness continuity between ECT sensor and ECM. Repair harness or connectors as necessary. - Ensure ECT sensor is not damaged or contaminated. Check ECM and ECT sensor harness connectors for damage, corrosion or pushed-out pins. Repair if necessary. If no problems are found, go to next step.
- Check Component
Ensure ignition is off. Measure resistance between ECT sensor harness connector terminals. Ensure resistance is as follows:- Coolant temperature 68°F (20°C); 2100-2900 ohms.
- Coolant temperature 122°F (50°C); 680-1000 ohms.
- Coolant temperature 194°F (90°C); 236-260 ohms.
If resistance is not as specified, replace ECT sensor.