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Home › Infiniti › 2007 › 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: Checking Ground Connections
      G04900129Courtesy of NISSAN NORTH AMERICA, INC.

    OK or NG 

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. RETIGHTEN A/F SENSOR 1 
    1. Loosen and retighten the A/F sensor 1.
      Fig 2: Identifying Retighten A/F Sensor 1
      G04900286Courtesy of NISSAN NORTH AMERICA, INC.

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

    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 

    OK: GO TO 4.

    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 Display - "DATA MONITOR"
      G04900288Courtesy of NISSAN NORTH AMERICA, INC.

    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: Identifying Mass Air Flow (MAF) Sensor Harness Connector
      G04900191Courtesy of NISSAN NORTH AMERICA, INC.

    Yes or No 

    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 ".

    No: GO TO 5.

  5. CHECK HARNESS CONNECTOR 
    1. Turn ignition switch OFF.
    2. Disconnect A/F sensor 1 harness connector.
      Fig 5: Identifying A/F Sensor 1 Harness Connector
      G04900164Courtesy of NISSAN NORTH AMERICA, INC.
    3. Check harness connector for water.

      Water should not exit. 

    OK or NG 

    OK: GO TO 6.

    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 4 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG 

    OK: GO TO  8.

    NG: GO TO 7.

    Fig 6: Checking Voltage Between A/F Sensor 1 Terminal 4 And Ground
    G04874929Courtesy of NISSAN NORTH AMERICA, INC.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E5, F14
    • IPDM E/R harness connector E119
    • 15A fuse
    • Harness for open or short between A/F sensor 1 and fuse

      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 .

      TERMINALS CONTINUITY CHART

        A/F sensor 1 terminal ECM terminal
      Bank 1 1 35
      2 56
      Bank 2 1 16
      2 75

      Continuity should exist. 

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

      Refer to WIRING DIAGRAM .

      TERMINALS CONTINUITY CHART

      Bank 1 Bank 2
      A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal
      1 35 1 16
      2 56 2 75

      Continuity should not exist. 

    5. Also check harness for short to power.

    OK or NG 

    OK: GO TO 9.

    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 

    OK: GO TO 10.

    NG: GO TO  11.

  10. CHECK INTERMITTENT INCIDENT 

    Perform "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    OK or NG 

    OK: GO TO 11.

    NG: Repair or replace.

  11. REPLACE AIR FUEL RATIO (A/F) SENSOR 1 

    Replace malfunctioning 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.

    GO TO 12.

  12. CONFIRM A/F ADJUSTMENT DATA 
    1. Turn ignition switch OFF and then ON.
    2. Select "A/F ADJ-B1" and "A/F ADJ-B2" in "DATA MONITOR" mode with CONSULT-II.
    3. Make sure that "0.000" is displayed on CONSULT-II screen.
      Fig 7: Consult-II Display - Data Monitor
      G04900756Courtesy of NISSAN NORTH AMERICA, INC.

      INSPECTION END 

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