DTC P0122: Throttle/Pedal Position Sensor/Switch "A" Circuit Low: Notes

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Improper idling
Engine stalls.
Poor driving performance

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>CLEAR MEMORY MODE>OPERATION , and inspection mode Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>INSPECTION MODE>PROCEDURE ..
Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram:

Engine Electrical System Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

G11577080

Courtesy of SUBARU OF AMERICA, INC.

CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR.
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connectors from electronic throttle control.
4. Measure the resistance between the ECM connector and engine ground.
  Connector & terminal
  
  (E158) No. 18 - Engine ground:
  
  (E158) No. 17 - Engine ground:
Is the resistance 1 MΩ or more?

Yes: Go to 2.

No: Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.
CHECK SHORT CIRCUIT INSIDE THE ECM.
1. Connect the connector to ECM.
2. Measure the resistance between electronic throttle control connector and engine ground.
Connector & terminal

(E57) No. 1 - Engine ground:

Is the resistance 1 MΩ or more?

Yes: Replace the electronic throttle control. Refer to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>THROTTLE BODY .

No: Repair the ground short circuit of harness between ECM connector and electronic throttle control connector. Replace the ECM if defective. Refer to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>ENGINE CONTROL MODULE (ECM) .