DTC P0115 OR P0125: ENGINE COOLANT TEMPERATURE (ECT) SENSOR Infiniti I30 I

1. Check Power Supply - Turn ignition off. Disconnect ECT sensor harness connector. (Scheme 11) Turn ignition on. Measure voltage between ECT sensor harness connector terminal No. 2 (Yellow wire) and ground. If voltage is about 5 volts, go to next step. If voltage is not 5 volts, verify harness continuity of Yellow wire between ECT sensor and ECM. Repair harness or connectors as necessary.
2. Check Ground Circuit - Turn ignition off. Check ECT sensor harness continuity between terminal No. 1 (Black wire) and engine ground. 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.
3. Check Component - 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.
4. Ensure ignition is off. Measure resistance between ECT sensor harness connector terminals. Ensure resistance is as follows: Coolant temperature 68°F (20°C); 2500 ohms. Coolant temperature 122°F (50°C); 840 ohms. Coolant temperature 194°F (90°C); 250 ohms. If resistance is not as specified, replace ECT sensor.

Scheme 11