LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Nissan-Datsun >> 2004 >> Sentra Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - QG18DE >> DTC P2122, P2123: App Sensor >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

  1. RETIGHTEN GROUND SCREWS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten engine ground screws.
      1. : GO TO 2.
    Fig 1: Retightening Engine Ground Screws
    G00773342Courtesy of NISSAN MOTOR CO., U.S.A.
  2. CHECK APP SENSOR 1 POWER SUPPLY CIRCUIT 
    1. Disconnect accelerator pedal position (APP) sensor harness connector.
    2. Turn ignition switch ON.
      Fig 2: Disconnecting Accelerator Pedal Position (APP) Sensor Harness Connector
      G00773343Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between APP sensor terminal 2 and ground with CONSULT-II or tester. 
      1. Voltage: Approximately 5V 

    OK or NG 

    1. OK : GO TO  4
    2. NG : GO TO 3.
    Fig 3: Checking Voltage Between APP Sensor Terminal 2 And Ground
    G00773344Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors M58, F26
    • Harness for open or short between ECM and accelerator pedal position sensor
      1. : Repair open circuit or short to ground or short to power in harness or connectors.
  4. CHECK APP SENSOR 1 GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminal 82 and APP sensor terminal 4.

      Refer to WIRING DIAGRAM .

      1. Continuity should exist. 
    4. Also check harness for short to ground and short power.

    OK or NG 

    1. OK : GO TO  6
    2. NG : GO TO 5.
  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors M58, F26
    • Harness for open or short between ECM and accelerator pedal position sensor
      1. : Repair open circuit or short to ground or short to power in harness or connectors.
  6. CHECK APP SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between ECM terminal 106 and APP sensor terminal 3.

      Refer to WIRING DIAGRAM .

      1. Continuity should exist. 
    2. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK : GO TO  8
    2. NG : GO TO 7.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors M58, F26
    • Harness for open or short between ECM and accelerator pedal position sensor
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  8. CHECK APP SENSOR 

    Refer to COMPONENT INSPECTION .

    OK or NG 

    1. OK : GO TO 9.
    2. NG : Replace accelerator pedal assembly.
  9. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    1. INSPECTION END 

scientia non olet · About LEMON Manuals