DTC P0123 Throttle/Pedal Position Sensor/Switch "A" Circuit High: Wiring Diagram

Engine electrical system, 2.5 L model (without push button start). See appropriate SYSTEM WIRING DIAGRAM article.
Engine electrical system, 2.5 L model (with push button start). See appropriate SYSTEM WIRING DIAGRAM article.

Fig 1: Electronic Throttle Control Relay - Circuit Diagram (B220)
Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR. Turn the ignition switch to OFF. Disconnect the connectors from ECM and electronic throttle control. Measure the resistance of harness between ECM and electronic throttle control connector. Connector & terminal (B134) No. 18 - (E57) No. 6: (B134) No. 29 - (E57) No. 3:	Is the resistance less than 1 Ω?	Go to step 2 .	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit in harness between ECM and electronic throttle control connector Poor contact of coupling connector
2 CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR. Connect the connector to ECM. Measure the resistance between electronic throttle control connector and engine ground. Connector & terminal (E57) No. 3 - Engine ground:	Is the resistance less than 5 Ω?	Go to step 3 .	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit of harness between ECM and engine ground Poor contact of ECM connector Poor contact of coupling connector
3 CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR. Turn the ignition switch to ON. Measure the voltage between electronic throttle control connector and engine ground. Connector & terminal (E57) No. 6 (+) - Engine ground (-):	Is the voltage 5 V or more?	Repair the short circuit to power in harness between ECM and electronic throttle control connector.	Go to step 4 .
4 CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from ECM. Measure the resistance between ECM connectors. Connector & terminal (B134) No. 19 - (B134) No. 18:	Is the resistance 1 MΩ or more?	Repair the poor contact of electronic throttle control connector. Replace the electronic throttle control if defective. Refer to THROTTLE BODY .	Repair the short circuit to power in harness between ECM and electronic throttle control connector.