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Home >> Infiniti >> 2008 >> EX35 Base, AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P0137 To P0448 >> P0138, P0158 Ho2S2 >> Diagnosis Procedure
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Diagnosis Procedure

  1. INSPECTION START

    Confirm the detected malfunction (A or B). Refer to "DTC LOGIC ".

    Which malfunction is detected? 

    A: GO TO 2

    B: GO TO  9.

  2. CHECK GROUND CONNECTION
    1. Turn ignition switch OFF.
    2. Check ground connection M95. Refer to Ground Inspection in "CIRCUIT INSPECTION ".

    Is the inspection result normal? 

    YES: GO TO 3.

    NO: Repair or replace ground connection.

  3. CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT
    1. Disconnect heated oxygen sensor 2 (HO2S2)harness connector.
    2. Disconnect ECM harness connector.
    3. Check the continuity between HO2S2 harness connector and ECM harness connector.
      CONTINUITY SPECIFICATIONS

      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F54 1 F102 84 Existed
      P0158 2 F53 1
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal? 

    YES: GO TO 4.

    NO: 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 the continuity between HO2S2 harness connector and ECM harness connector.
      CONTINUITY SPECIFICATIONS

      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F54 4 F102 76 Existed
      P0158 2 F53 4 80
    2. Check the continuity between HO2S2 harness connector or ECM harness connector and ground.
      CONTINUITY SPECIFICATIONS

      DTC HO2S2 ECM Ground Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F54 4 F102 76 Ground Not existed
      P0158 2 F53 4 80
    3. Also check harness for short to power.

    Is the inspection result normal? 

    YES: GO TO 5.

    NO: Repair open circuit or short to ground or short to power in harness or connectors.

  5. CHECK HO2S2 CONNECTOR FOR WATER

    Check connectors for water.

    Water should not exist. 

    Is the inspection result normal? 

    YES: GO TO 6.

    NO: Repair or replace harness or connectors.

  6. CHECK HEATED OXYGEN SENSOR 2

    Refer to "COMPONENT INSPECTION ".

    Is the inspection result normal? 

    YES: GO TO  8.

    NO: GO TO 7.

  7. REPLACE HEATED OXYGEN SENSOR 2

    Replace malfunctioning heated oxygen sensor 2.

    CAUTION:
    • Discard any heated oxygen 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 oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner [commercial service tool (J-43897-18 or J-43897-12)] and approved anti-seize lubricant (commercial service tool).

    INSPECTION END

  8. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    INSPECTION END

  9. CHECK GROUND CONNECTION
    1. Turn ignition switch OFF.
    2. Check ground connection M95. Refer to Ground Inspection in "CIRCUIT INSPECTION ".

    Is the inspection result normal? 

    YES: GO TO 10.

    NO: Repair or replace ground connection.

  10. CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE
    1. Clear the mixture ratio self-learning value. Refer to "MIXTURE RATIO SELF-LEARNING VALUE CLEAR : SPECIAL REPAIR REQUIREMENT ".
    2. Run engine for at least 10 minutes at idle speed.

    Is the 1st trip DTC P0172 or P0175 detected? Is it difficult to start engine? 

    YES: Perform trouble diagnosis for DTC P0172, P0175. Refer to "DTC LOGIC ".

    NO: GO TO 11.

  11. CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect heated oxygen sensor 2 harness connector.
    3. Disconnect ECM harness connector.
    4. Check the continuity between HO2S2 harness connector and ECM harness connector.
      CONTINUITY SPECIFICATIONS

      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F54 1 F102 84 Existed
      P0158 2 F53 1
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal? 

    YES: GO TO 12.

    NO: Repair open circuit or short to ground or short to power in harness or connectors.

  12. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Check the continuity between HO2S2 harness connector and ECM harness connector.
      CONTINUITY SPECIFICATIONS

      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F54 4 F102 76 Existed
      P0158 2 F53 4 80
    2. Check the continuity between HO2S2 harness connector or ECM harness connector and ground.
      CONTINUITY SPECIFICATIONS

      DTC HO2S2 ECM Ground Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F54 4 F102 76 Ground Not existed
      P0158 2 F53 4 80
    3. Also check harness for short to power.

    Is the inspection result normal? 

    YES: GO TO 13.

    NO: Repair open circuit or short to ground or short to power in harness or connectors.

  13. CHECK HEATED OXYGEN SENSOR 2

    Refer to "COMPONENT INSPECTION ".

    Is the inspection result normal? 

    YES: GO TO  15.

    NO: GO TO 14.

  14. REPLACE HEATED OXYGEN SENSOR 2

    Replace malfunctioning heated oxygen sensor 2.

    CAUTION:
    • Discard any heated oxygen 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 oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner [commercial service tool (J-43897-18 or J-43897-12)] and approved anti-seize lubricant (commercial service tool).

    INSPECTION END

  15. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    INSPECTION END

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