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Home › Nissan-Datsun › 2005 › Pathfinder LE, 4WD › Repair and Diagnosis › Engine Performance › Engine Control System › DTC P1279, P1289: A/F Sensor 1 › Diagnostic Procedure

Diagnostic Procedure

  1. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten three ground screws on the body. Refer to GROUND INSPECTION .
      Fig 1: Locating Ground Screws Of Body
      G02432264Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    • OK: GO TO 2.
    • NG: Repair or replace ground connections.
  2. RETIGHTEN AIR FUEL RATIO (A/F) SENSOR 1 

    Loosen and retighten the air fuel ratio (A/F) sensor 1.

    Fig 2: Locating Air Fuel Ratio (A/F) Sensor 1
    G02432265Courtesy of NISSAN MOTOR CO., U.S.A.
    • Tightening torque: 50 N.m (5.1 kg-m, 37 ft-lb) 
    • GO TO 3.
  3. CHECK EXHAUST GAS LEAK 
    1. Start engine and run it at idle.
    2. Listen for an exhaust gas leak before three way catalyst (manifold).
      Fig 3: Checking Exhaust Gas Leakage
      G02432266Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    • OK: GO TO 4.
    • NG: Repair or replace.
  4. CHECK FOR INTAKE AIR LEAK 

    Listen for an intake air leak after the mass air flow sensor.

    OK or NG 

    • OK: GO TO 5.
    • NG: Repair or replace.
  5. 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.
      Fig 4: CONSULT-II Display - WORK SUPPORT MODE
      G02432267Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Clear the self-learning control coefficient by touching "CLEAR" or "START".
    4. Run engine for at least 10 minutes at idle speed.

      Is the 1st trip DTC P0171, P172, P0174 or P0175 detected? Is it difficult to start engine? 

    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.
      Fig 5: Identifying Mass Air Flow Sensor
      G02432268Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Restart engine and let it idle for at least 3 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? 

    Yes or No 

  6. CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect air fuel ratio (A/F) sensor 1 harness connector.
      Fig 6: Locating Air Fuel Ratio (A/F) Sensor 1 Harness Connector
      G02432269Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Turn ignition switch ON.
    4. Check voltage between air fuel ratio (A/F) sensor 1 terminal 3 and ground with CONSULT-II or tester.
      • Voltage: Battery voltage 
      Fig 7: Checking Voltage Between Air Fuel Ratio (A/F) Sensor 1 Connector Terminal 3 And Ground
      G02432270Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    • OK: GO TO  8.
    • NG: GO TO 7.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E5, F14
    • IPDM E/R connector E119
    • 10A fuse
    • Harness for open or short between air fuel ratio (A/F) sensor 1 and fuse
      • Repair or replace harness or connectors.
  8. CHECK AIR FUEL RATIO (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 the following terminals. Refer to Fig 8 and WIRING DIAGRAM .
      Fig 8: ECM Terminals And A/F Sensor 1 Terminals Reference Chart (Continuity)
      G02432271Courtesy of NISSAN MOTOR CO., U.S.A.
      • Continuity should exist. 
    4. Check harness continuity between the following terminals and ground. Refer to Fig 9 and WIRING DIAGRAM .
      Fig 9: ECM Terminals And A/F Sensor 1 Terminals Reference Chart (Continuity To Ground)
      G02432272Courtesy of NISSAN MOTOR CO., U.S.A.
      • Continuity should not exist. 
    5. Also check harness for short to ground and 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 AIR FUEL RATIO (A/F) SENSOR 1 HEATER 

    Refer to COMPONENT INSPECTION .

    OK or NG 

    • OK: GO TO 10.
    • NG: GO TO  13.
  10. CHECK MASS AIR FLOW SENSOR 

    Refer to COMPONENT INSPECTION .

    OK or NG 

    • OK: GO TO 11.
    • NG: Replace mass air flow sensor.
  11. CHECK PCV VALVE 

    Refer to POSITIVE CRANKCASE VENTILATION .

    OK or NG

    • OK: GO TO 12.
    • NG: Repair or replace PCV valve.
  12. CHECK INTERMITTENT INCIDENT 

    Perform , "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    OK or NG 

    • OK: GO TO 13.
    • NG: Repair or replace.
  13. REPLACE AIR FUEL RATIO (A/F) SENSOR 1 

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

    CAUTION:
    • Discard any air fuel ratio (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 air fuel ratio (A/F) sensor, clean exhaust system threads using Heated Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
    • INSPECTION END
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