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Home >> Infiniti >> 2006 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P1225 To P2A03 >> DTC P2A00, P2A03 A/F Sensor 1 >> Diagnostic Procedure

Diagnostic Procedure

  1. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten two ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 1: Locating Body Ground Screws
      G04185036Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO 2.
    2. NG : Repair or replace ground connections.
  2. RETIGHTEN A/F SENSOR 1 
    1. Loosen and retighten the A/F sensor 1.
      Fig 2: Loosening And Retightening A/F Sensor 1
      G04133210Courtesy of NISSAN MOTOR CO., U.S.A.

      Tightening torque: 50 N-m (5.1 kg-m, 37 ft-lb) 

    1. : GO TO 3.
  3. CHECK FOR INTAKE AIR LEAK 
    1. Start engine and run it at idle.
    2. Listen for an intake air leak after the mass air flow sensor.

    OK or NG 

    1. OK : GO TO 4.
    2. NG : Repair or replace.
  4. CLEAR THE SELF-LEARNING DATA 

    With CONSULT-II 

    1. Start engine and warm it up to normal operating temperature.
    2. Select " SELF-LEARNING CONT" in " WORK SUPPORT" mode with CONSULT-II.
    3. Clear the self-learning control coefficient by touching " CLEAR".
    4. Run engine for at least 10 minutes at idle speed.

      Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? 

      Is it difficult to start engine? 

      Fig 3: Consult-II WORK SUPPORT Display Screen
      G04080618Courtesy of NISSAN MOTOR CO., U.S.A.

    Without CONSULT-II 

    1. Start engine and warm it up to normal operating temperature.
    2. Turn ignition switch OFF.
    3. Disconnect mass air flow sensor harness connector.
    4. Restart engine and let it idle for at least 5 seconds.
    5. Stop engine and reconnect mass air flow sensor harness connector.
    6. Make sure DTC P0102 is displayed.
    7. Erase the DTC memory. Refer to "HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION ".
    8. Make sure DTC P0000 is displayed.
    9. Run engine for at least 10 minutes at idle speed.

      Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? 

      Is it difficult to start engine? 

      Fig 4: Locating Mass Airflow Sensor
      G04132678Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No 

    1. Yes : Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to "DTC P0171, P0174 FUEL INJECTION SYSTEM FUNCTION " or "DTC P0172, P0175 FUEL INJECTION SYSTEM FUNCTION ".
    2. No : GO TO 5.
  5. CHECK HARNESS CONNECTOR 
    1. Turn ignition switch OFF.
    2. Disconnect A/F sensor 1 harness connector.
      Fig 5: Locating A/F Sensor 1 Banks 1/2 And Connectors
      G04185050Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check harness connector for water.

      Water should not exit. 

    OK or NG 

    1. OK : GO TO 6.
    2. NG : Repair or replace harness connector.
  6. CHECK A/F SENSOR 1 POWER SUPPLY CIRCUIT 
    1. Turn ignition switch ON.
    2. Check voltage between A/F sensor 1 terminal 3 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG 

    1. OK : GO TO  8.
    2. NG : GO TO 7.
      Fig 6: Identifying Voltage Between Connector Terminal 3 and Ground
      G04080486Courtesy of NISSAN MOTOR CO., U.S.A.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E5, F14
    • IPDM E/R harness connector E119
    • 10A fuse
    • Harness for open or short between A/F sensor 1 and fuse
      1. : Repair or replace harness or connectors.
  8. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between A/F sensor 1 terminal and ECM terminal as follows.

      Refer to WIRING DIAGRAM .

      A/F SENSOR 1 AND ECM TERMINALS

        A/F sensor 1 terminal ECM terminal
      Bank 1 1 16
      2 75
      5 35
      6 56
      Bank 2 1 76
      2 77
      5 57
      6 58

      Continuity should exist. 

    4. Check harness continuity between the following terminals and ground.

      Refer to WIRING DIAGRAM .

      BANK 1 AND BANK 2 A/F SENSOR 1 AND ECM TERMINALS

      Bank 1 Bank 2
      A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal
      1 16 1 76
      2 75 2 77
      5 35 5 57
      6 56 6 58

      Continuity should not exist. 

    5. Also check harness for short to power.

    OK or NG 

    1. OK : GO TO 9.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
  9. CHECK A/F SENSOR 1 HEATER 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK : GO TO 10.
    2. NG : GO TO  11.
  10. CHECK INTERMITTENT INCIDENT 

    Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    OK or NG 

    1. OK : GO TO 11.
    2. NG : Repair or replace.
  11. REPLACE AIR FUEL RATIO (A/F) SENSOR 1 

    Replace air fuel ratio (A/F) sensor 1.

    CAUTION:
    • Discard any A/F sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
    • Before installing new A/F sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
    1. : INSPECTION END