LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2005 >> Forester XT, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Controls - Engine (Diagnostics) (H4SO)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P2127: Throttle/Pedal Position Sensor/Switch "E" Circuit Low Input
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P2127: Throttle/Pedal Position Sensor/Switch "E" Circuit Low Input

WARNING: This page is about a different variant/trim than selected.

DTC DETECTING CONDITION: 

TROUBLE SYMPTOM: 

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to , OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to , PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM: 

Fig 1: DTC P2127 Throttle/Pedal Position - Wiring Diagram And Connector Terminal
G03806126Courtesy of SUBARU OF AMERICA, INC.
DIAGNOSTIC PROCEDURE DTC P2127

Step Check Yes No
1 CHECK OUTPUT VOLTAGE OF ACCELERATOR PEDAL POSITION SENSOR. 
  1. Turn the ignition switch to ON.
  2. Read the data of sub accelerator pedal position sensor signal using Subaru Select Monitor.
Is the voltage more than 0.4 V? Go to step . Go to step .
2 CHECK POOR CONTACT IN CONNECTORS. 
Check poor contact in connectors between ECM and accelerator pedal position sensor.
Is there any poor contact in connectors between ECM and accelerator pedal position sensor? Repair the poor contact in connectors. Connector has returned to its normal condition at this time. A temporary poor contact in the connector might have been the cause.
3 CHECK HARNESS BETWEEN ECM AND ACCELERATOR PEDAL POSITION SENSOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from ECM.
  3. Disconnect the connector from accelerator pedal position sensor.
  4. Measure the resistance between ECM connector and accelerator pedal position sensor.

Connector & terminal 
(B136) No. 28 - (B315) No. 2: 
(B136) No. 16 - (B315) No. 1  :
Is the resistance less than 1 Ω? Go to step . Repair the open harness connector.
4 CHECK HARNESS BETWEEN ECM AND ACCELERATOR PEDAL POSITION SENSOR. 
Measure the resistance between ECM connector and chassis ground.
Connector & terminal 
(B136) No. 28 - Chassis ground: 
(B136) No. 16 - Chassis ground: 
Is the resistance more than 1 MΩ? Go to step . Repair the ground short of harness.
5 CHECK POWER SUPPLY TO ACCELERATOR PEDAL POSITION SENSOR. 
  1. Connect the ECM connector.
  2. Turn the ignition switch to ON.
  3. Measure the voltage between accelerator pedal position sensor connector and chassis ground.

Connector & terminal 
(B315) No. 1 (+) - Chassis ground (-): 
Is the voltage 4.5 - 5.5 V? Go to step . Repair the poor contact in ECM connector. If problem persists, replace the ECM.
< Ref. to ENGINE CONTROL MODULE (ECM) . >
6 CHECK ACCELERATOR PEDAL POSITION SENSOR. 
Measure the resistance of accelerator pedal position sensor.
Terminals 
No. 1 - No. 6: 
Is the resistance 0.75 - 3.15 kΩ? Go to step . Replace the accelerator pedal position sensor.
7 CHECK ACCELERATOR PEDAL POSITION SENSOR. 
Measure the resistance of accelerator pedal position sensor when accelerator pedal is released.
Terminals 
No. 2 - No. 6: 
Is the resistance 0.15 - 0.63 kΩ? Go to step . Replace the accelerator pedal position sensor.
8 CHECK ACCELERATOR PEDAL POSITION SENSOR. 
Measure the resistance of accelerator pedal position sensor when acceleration pedal is being depressed.
Terminals 
No. 2 - No. 6: 
Is the resistance 0.28 - 1.68 kΩ? Repair the poor contact in ECM connector. If problem persists, replace the ECM.
< Ref. to ENGINE CONTROL MODULE (ECM) . >
Replace the accelerator pedal position sensor.