DTC P0118 (TW_HI): ECT SENSOR CIRCUIT HIGH INPUT (FORESTER & IMPREZA)

DTC P0118 (TW_HI): ECT SENSOR CIRCUIT HIGH INPUT (FORESTER & IMPREZA) Subaru Forester SF

Turn ignition off. Connect scan tool. Start engine. Observe coolant temperature display. If displayed value is more than -40°F (-40°C), repair poor contact in connectors or wiring of ECT sensor connector or PCM connector. If displayed value is less than -40°F (-40°C), go to next step.
Turn ignition off. Remove idle air control solenoid valve by-pass air hose. Remove crankcase blow-by hoses and engine harness connector bracket to gain access to ECT sensor connector. Disconnect ECT sensor connector. Using a voltmeter connected to ground, check voltage at ECT sensor connector terminal No. 1 (Black/Yellow wire). If voltage reading is more than 10 volts, repair short circuit in wiring between ECT sensor connector and PCM connector. If voltage reading is 10 volts or less, leave voltmeter connected and go to next step.
Turn ignition on. If voltage reading is more than 10 volts, repair short circuit in wiring between ECT sensor connector and PCM connector. If voltage reading is 4 volts or less, check for an open or poor contact in connectors or wiring of ECT sensor or PCM connectors. If voltage reading is 4-10 volts, go to next step.
Turn ignition off. Using an ohmmeter, measure resistance of harness between ground and ECT sensor connector terminal No. 2 (Black wire). If resistance is less than 5 ohms, replace ECT sensor. If resistance is more than 5 ohms, repair open or poor contact in connectors or wiring of ECT sensor PCM connectors.

DTC P0118 (TW_HI): ECT SENSOR CIRCUIT HIGH INPUT (FORESTER & IMPREZA) Subaru Forester SF