DTC P0123: Throttle Position (TP) Sensor Circuit High Input
- Perform test procedure. See TESTING PROCEDURE . Start engine. Using a scan tool, monitor Throttle Position (TP) sensor signal. If TP sensor signal value is more than 4.9 volts, go to next step. If TP sensor signal value is not more than 4.9 volts, circuit has returned to normal. Check for intermittent conditions. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES and VERIFICATION PROCEDURE .
- Turn ignition off. Disconnect 4-pin electrical harness connector from TP sensor. Using a DVOM, measure resistance between TP sensor 4-pin electrical harness connector terminal No. 2 (Green wire on Forester; Black/Red wire on Impreza and Outback Sport; Black wire on Legacy and Outback) and good engine ground point. See Figure. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, locate and repair open circuit in wiring between ECM and TP sensor. Also check for poor contact in all connectors between TP sensor and ECM. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES and VERIFICATION PROCEDURE .
- Turn ignition on. Using a DVOM, measure voltage between TP sensor 4-pin electrical harness connector terminal No. 3 (White/Black wire on Forester; White/Red wire on Impreza and Outback Sport; White wire on Legacy and Outback) and good engine ground point. See Figure. If voltage is more than 4.9 volts, repair short to voltage in wiring between ECM and TP sensor. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. After repair, replace ECM. If voltage is not more than 4.9 volts, replace TP sensor. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES and VERIFICATION PROCEDURE .