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
Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>General Description>PREPARATION TOOL>HOW TO USE CHECK BOARD .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Basic Diagnostic Procedure>PROCEDURE .

CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to OPERATION .
Is DTC P0122 displayed? (Current code)

Yes : Go to 2.

No : Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
CHECK FOR POOR CONTACT .
1. Turn the ignition switch to OFF.
2. Check for poor contact of ECM and electronic throttle control connector.
Is there poor contact in ECM or electronic throttle control connector?

Yes : Repair the poor contact of the ECM or electronic throttle control connector.

No : Go to 3.
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR (OPEN) .
1. Disconnect the connector from ECM.
2. Disconnect the connectors from electronic throttle control.
3. Measure the resistance of harness between ECM connector and electronic throttle control connector.
Connector & terminal

(E158) No. 34 - (E57) No. 1:

(E158) No. 49 - (E57) No. 2:

Is the resistance less than 1 Ω?

Yes : Go to 4.

No : Repair the open circuit of harness between ECM connector and electronic throttle control connector.
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR (SHORT TO GROUND) .
1. Measure the resistance between the ECM connector and engine ground.
  Connector & terminal
  
  (E158) No. 34 - Engine ground:
  
  (E158) No. 49 - Engine ground:
Is the resistance 1 MΩ or more?

Yes : Go to 5.

No : Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.
CHECK SHORT CIRCUIT INSIDE ECM .
1. Connect the connector to ECM.
2. Turn the ignition switch to ON.
3. Measure the resistance between electronic throttle control connector and engine ground.
  Connector & terminal
  
  (E57) No. 1 - Engine ground:
Is the voltage 4.5 - 5.5 V?

Yes : Replace the electronic throttle control. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>THROTTLE BODY .

No : Repair the ground short circuit of harness between ECM connector and electronic throttle control connector. When there is no ground short circuit in the harness, replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>ENGINE CONTROL MODULE (ECM) .