DTC P0118 - ENGINE COOLANT TEMPERATURE (ECT) SENSOR HIGH VOLTAGE INPUT Honda Civic VI

1. Turn ignition on. Check ECT using OBD-II scan tool. If -4°F (-20°C) or less is indicated, go to next step. If -4°F (-20°C) or less is not indicated, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at ECT sensor connector and PCM connector. See «WIRING DIAGRAMS»(ref-16355) article.
2. Disconnect ECT sensor connector. Install a fused jumper wire between ECT harness connector terminals. Check ECT using OBD-II scan tool. If -4°F (-20°C) or less is indicated, go to next step. If -4°F (-20°C) or less is not indicated, replace ECT sensor.
3. Turn ignition off. Using backprobe kit, install a fused jumper wire between PCM 16-pin connector "D" terminal D2 (Red/White wire) and terminal D11 (Green/Black wire). Turn ignition on. Check ECT using OBD-II scan tool. If -4°F (-20°C) or less is not indicated, repair open in wire(s) between ECT sensor and PCM connector terminals. See «WIRING DIAGRAMS»(ref-16355) article. If -4°F (-20°C) or less is indicated, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.

Scheme 26

1. Turn ignition on. Using OBD-II scan tool, check throttle position. If reading is about 10 percent with throttle fully closed and 90 percent with throttle fully opened, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at TP sensor connector and PCM connector. See «WIRING DIAGRAMS»(ref-16355) article. If reading is not as specified, go to next step.
2. Turn ignition off. Disconnect TP sensor 3-pin connector. Turn ignition on. Measure voltage between TP sensor harness connector terminal No. 1 (Green/Black wire) and terminal No. 3 (Yellow/Blue wire). see scheme 6 If about 5.0 volts does not exist, go to next step. If about 5.0 volts exists, go to step 4).
3. Using backprobe kit, measure voltage between PCM 16-pin connector "D" terminal D10 (Yellow/Blue wire) and terminal D11 (Green/Black wire). see scheme 4 If about 5.0 volts exists, repair open in Yellow/Blue wire between PCM connector terminal D10 and TP sensor. See «WIRING DIAGRAMS»(ref-16355) article. If about 5.0 volts does not exist, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.
4. Turn ignition off. Measure resistance between TP sensor terminals No. 1 and 2 with throttle fully closed. (Scheme 26) If resistance is about 500-900 ohms, go to next step. If resistance is not as specified, replace throttle body (TP sensor cannot be serviced separately).
5. Measure resistance between TP sensor terminals No. 2 and 3 with throttle fully closed. If resistance is about 3600-5400 ohms, go to next step. If resistance is not as specified, replace throttle body (TP sensor cannot be serviced separately).
6. Reconnect TP sensor 3-pin connector. Turn ignition on. Using backprobe kit, measure voltage between PCM 16-pin connector "D" terminal D1 (Red/Black wire) and terminal D11 (Green/Black wire). see scheme 4 If voltage is about 0.5 volt with throttle fully closed and 4.5 volts with throttle fully open, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. On D16Y5 engine with CVT, if voltage is not as specified, go to next step. On all other engines, if voltage is not as specified, repair short in Red/Black wire between PCM connector and TP sensor.
7. On D16Y5 engine with CVT, turn ignition off. Disconnect TCM 22-pin connector. TCM is located behind driver side kick panel. Turn ignition on. Using backprobe kit, measure voltage between PCM 16-pin connector "D" terminal D1 (Red/Black wire) and terminal D11 (Green/Black wire). If voltage is about 0.5 volt with throttle fully closed and 4.5 volts with throttle fully open, replace Transmission Control Module (TCM). If voltage is not as specified, repair short in Red/Black wire between PCM connector and TP sensor. See «WIRING DIAGRAMS»(ref-16355) article.