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Home >> Infiniti >> 2024 >> QX55 Essential >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (DTC/Circuit Diagnosis) (1 Of 4) >> DTC/Circuit Diagnosis >> P0136 O2 Sensor Bank 1 Sensor 2 >> Diagnosis Procedure
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Diagnosis Procedure

  1. INSPECTION START 

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

    Which malfunction is detected?

    A>>

    GO TO 2.

    B>>

    GO TO 7.

  2. CHECK HEATED OXYGEN SENSOR 2 CONNECTOR 
    1. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
    2. Check that water is not inside connectors.
    There is no leakage.

    Is the inspection result normal?

    >>

    GO TO 3.

    >>

    Repair or replace malfunctioning part.

  3. CHECK HO2S2 GROUND CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
    4. Check the continuity between HO2S2 harness connector and ECM harness connector.
      HO2S2 ECM Continuity
      Connector Terminal Connector Terminal
      E39 1 F52 76 Existed
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    >>

    GO TO 4.

    >>

    Repair or replace malfunctioning part.

  4. CHECK HO2S2 INPUT SIGNAL CIRCUIT 
    1. Check the continuity between HO2S2 harness connector and ECM harness connector.
      HO2S2 ECM Continuity
      Connector Terminal Connector Terminal
      E39 2 F52 77 Existed
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.
      HO2S2 - Continuity
      Connector Terminal
      E39 2 Ground Not existed
      ECM - Continuity
      Connector Terminal
      F52 77 Ground Not existed
    3. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    >>

    GO TO 5.

    >>

    Repair or replace malfunctioning part.

  5. CHECK HEATED OXYGEN SENSOR 2 

    Refer to Component Inspection .

    Is the inspection result normal?

    >>

    INSPECTION END

    >>

    GO TO 6.

  6. REPLACE HEATED OXYGEN SENSOR 2 

    Replace heated oxygen sensor 2. Refer to Exploded View .

    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.

    >>

    INSPECTION END

  7. PERFORM AIR FUEL RATIO INITIAL LEARNING 
    1. Start engine and warm it up to the normal operating temperature.
    2. Clear the air fuel ratio initial learning. Refer to Work Procedure .
    3. Run engine for at least 10 minutes at idle speed.

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

    >>

    Perform trouble diagnosis for DTC P0172. Refer to Diagnosis Procedure .

    >>

    GO TO 8.

  8. CHECK HEATED OXYGEN SENSOR 2 GROUND CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
    4. Check the continuity between HO2S2 harness connector and ECM harness connector.
      HO2S2 ECM Continuity
      Connector Terminal Connector Terminal
      E39 1 F52 76 Existed
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    >>

    GO TO 9.

    >>

    Repair or replace malfunctioning part.

  9. CHECK HO2S2 INPUT SIGNAL CIRCUIT 
    1. Check the continuity between HO2S2 harness connector and ECM harness connector.
      HO2S2 ECM Continuity
      Connector Terminal Connector Terminal
      E39 2 F52 77 Existed
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.
      HO2S2 - Continuity
      Connector Terminal
      E39 2 Ground Not existed
      ECM - Continuity
      Connector Terminal
      F52 77 Ground Not existed
    3. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    >>

    GO TO 10.

    >>

    Repair or replace malfunctioning part.

  10. CHECK HEATED OXYGEN SENSOR 2 

    Refer to Component Inspection .

    Is the inspection result normal?

    >>

    INSPECTION END

    >>

    GO TO 11.

  11. REPLACE HEATED OXYGEN SENSOR 2 

    Replace heated oxygen sensor 2. Refer to Exploded View .

    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.

    >>

    INSPECTION END

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