DTC P0118: Engine Coolant Temp. (ECT) Circuit High Input

NOTE: If DTC P0108, P0113, P0118, P0123 and/or P0450 are set together, check Light Green/Black wire (terminal No. 9, PCM 16-pin harness connector) for open circuit.

Connect scan tool to Data Link Connector (DLC). Turn ignition on. Observe engine coolant temperature displayed on scan tool. If display reads -40°F (-40°C), go to next step. If display reading is not as specified, check for an intermittent problem. See TESTS W/O CODES article.
Turn ignition off. Disconnect ECT sensor harness connector located near coolant outlet. Turn ignition on. Using a voltmeter, measure voltage between ground and Gray/White wire on ECT sensor harness connector. If reading is 4-6 volts, go to next step. If reading is greater than 4-6 volts, check Gray/White wire for short to battery power. Repair as necessary. Retest system.
Turn ignition off. Disconnect PCM 16-pin harness connector. Using an ohmmeter, check for continuity between Light Green/Black wire on ECT sensor harness connector and terminal No. 9 on PCM 16-pin harness connector. If continuity exists, go to next step. If continuity does not exist, check Light Green/Black wire for open or poor connection. Repair as necessary. Retest system. 4) Reconnect PCM connector. Turn ignition on. Connect fused jumper wire between ECT sensor harness connector terminals. If display on scan tool reads 246°F (119°C), replace ECT sensor. If display reading is not as specified, replace PCM. Retest system.