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Home >> Infiniti >> 2015 >> QX60 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (Engine Control System (DTC/Circuit Diagnosis) (VQ35DE) (Except Hybrid) (1 Of 3)) >> DTC/Circuit Diagnosis >> DTC P0138, P0158: Ho2S2 >> Diagnosis Procedure >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2016 Infiniti QX60. However, it is still accessible from the selected car via links, so may be relevant.

  1. INSPECTION START

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

    Which malfunction is detected?

    A 

    GO TO STEP 2. 

    B 

    GO TO STEP   6 . 

  2. CHECK HO2S2 CONNECTOR FOR WATER

    1. Disconnect heated oxygen sensor 2 harness connector.
    2. Check that water is not inside connectors.

    Is the inspection result normal?

    YES 

    GO TO STEP 3  .

    NO 

    Repair or replace harness or connectors.

  3. CHECK HO2S2 GROUND CIRCUIT

    1. Disconnect heated oxygen sensor 2 harness connector.
    2. Disconnect ECM harness connector.
    3. Check the continuity between heated oxygen sensor 2 (HO2S2) harness connector and ECM harness connector.
      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F75 4 F78 35 Existed
      P0158 2 F76 4
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES 

    GO TO STEP 4  .

    NO 

    Repair open circuit, short to ground or short to power in harness or connectors.

  4. CHECK HO2S2 INPUT SIGNAL CIRCUIT

    1. Check the continuity between HO2S2 harness connector and ECM harness connector.
      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F75 3 F78 41 Existed
      P0158 2 F76 3 32
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.
      DTC HO2S2 Ground Continuity
      Bank Connector Terminal
      P0138 1 F75 3 Ground Not existed
      P0158 2 F76 3
      DTC ECM Ground Continuity
      Connector Terminal
      P0138 F78 41 Ground Not existed
      P0158 32
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES 

    GO TO STEP 5  .

    NO 

    Repair open circuit, short to ground or short to power in harness or connectors.

  5. CHECK HEATED OXYGEN SENSOR 2

    Check heated oxygen sensor 2. Refer to COMPONENT INSPECTION .

    Is the inspection result normal?

    YES 

    Check intermittent incident. Refer to INTERMITTENT INCIDENT .

    NO 

    Replace malfunctioning heated oxygen sensor 2. Refer to REMOVAL AND INSTALLATION (BANK 2) , REMOVAL AND INSTALLATION (BANK 1) .

  6. CLEAR MIXTURE RATIO SELF-LEARNING VALUE

    1. Clear the mixture ratio self-learning value. Refer to DESCRIPTION .
    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 STEP 7  .

  7. CHECK HO2S2 GROUND CIRCUIT

    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.
      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F75 4 F78 35 Existed
      P0158 2 F76 4
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES 

    GO TO STEP 8  .

    NO 

    Repair open circuit, short to ground or short to power in harness or connectors.

  8. CHECK HO2S2 INPUT SIGNAL CIRCUIT

    1. Check the continuity between HO2S2 harness connector and ECM harness connector.
      DTC HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      P0138 1 F75 3 F78 41 Existed
      P0158 2 F76 3 32
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.
      DTC HO2S2 Ground Continuity
      Bank Connector Terminal
      P0138 1 F75 3 Ground Not existed
      P0158 2 F76 3
      DTC ECM Ground Continuity
      Connector Terminal
      P0138 F78 41 Ground Not existed
      P0158 32
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES 

    GO TO STEP 9  .

    NO 

    Repair open circuit, short to ground or short to power in harness or connectors.

  9. CHECK HEATED OXYGEN SENSOR 2

    Check heated oxygen sensor 2. Refer to COMPONENT INSPECTION 

    Is the inspection result normal?

    YES 

    Check intermittent incident. Refer to INTERMITTENT INCIDENT .

    NO 

    Replace malfunctioning heated oxygen sensor 2. Refer to REMOVAL AND INSTALLATION (BANK 2) , REMOVAL AND INSTALLATION (BANK 1) .

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