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Home >> Nissan-Datsun >> 2005 >> Quest Base >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> DTC P0139, P0159: Ho2S2 >> Diagnostic Procedure
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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: Checking Ground Connections
      G02446980Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    • OK: GO TO 2.
    • NG: Repair or replace ground connections.
  2. 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 2: CONSULT-II Work Support Screen Display
      G02446981Courtesy 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 3: Disconnecting Mass Air Flow Sensor Harness Connector
      G02446982Courtesy of NISSAN MOTOR CO., U.S.A.

    Yes or No

  3. CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Disconnect heated oxygen sensor 2 harness connector.
      Fig 4: Disconnecting Heated Oxygen Sensor 2 Harness Connector
      G02446983Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Check harness continuity between ECM terminal 78 and HO2S2 terminal 4. Refer to WIRING DIAGRAM .
      • Continuity should exist. 
    5. Also check harness for short to ground and short to power.

    OK or NG

    • OK: GO TO 4.
    • NG: Repair open circuit or short to ground or short to power in harness or connectors.
  4. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between ECM terminal and HO2S2 terminal as follows. Refer to WIRING DIAGRAM .
      Fig 5: ECM Terminal & HO2S2 Terminal Connection Chart
      G02446984Courtesy of NISSAN MOTOR CO., U.S.A.
      • Continuity should exist. 
    2. Check harness continuity between the following terminals and ground. Refer to WIRING DIAGRAM .
      Fig 6: ECM Terminal HO2S2 Terminal Connection Chart
      G02446985Courtesy of NISSAN MOTOR CO., U.S.A.
      • Continuity should not exist. 
    3. Also check harness for short to power.

    OK or NG

    • OK: GO TO 5.
    • NG: Repair open circuit or short to ground or short to power in harness or connectors.
  5. CHECK HEATED OXYGEN SENSOR 2 

    Refer to "COMPONENT INSPECTION ".

    OK or NG

    • OK: GO TO 6.
    • NG: Replace malfunctioning heated oxygen sensor 2.
  6. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    • : INSPECTION END 
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