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Home >> Nissan-Datsun >> 2021 >> NV2500 HD S >> Repair and Diagnosis >> External Pages >> Different car >> Section 86 (Engine Control System (DTC/Circuit Diagnosis) (2 Of 5)) >> DTC/Circuit Diagnosis >> DTC P0138: Ho2S2 >> Diagnosis Procedure

Diagnosis Procedure

WARNING: This page is about a different car, the 2018 Nissan Maxima. 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 Description .

    Which malfunction is detected?

    A

    GO TO 2.

    B

    GO TO 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 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

      F62

      4

      F13

      35

      Existed

      P0158

      2

      F56

      4
    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, 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

      F62

      3

      F13

      41

      Existed

      P0158

      2

      F56

      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

      F62

      3

      Ground

      Not existed

      P0158

      2

      F56

      3

      DTC

      ECM

      Ground

      Continuity

      Connector

      Terminal

      P0138

      F13

      41

      Ground

      Not existed

      P0158

      32
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES

    GO TO 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

    INSPECTION END

    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 Description .

    NO

    GO TO 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

      F62

      4

      F13

      35

      Existed

      P0158

      2

      F56

      4
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES

    GO TO 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

      F62

      3

      F13

      41

      Existed

      P0158

      2

      F56

      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

      F62

      3

      Ground

      Not existed

      P0158

      2

      F56

      3

      DTC

      ECM

      Ground

      Continuity

      Connector

      Terminal

      P0138

      F13

      41

      Ground

      Not existed

      P0158

      32
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES

    GO TO 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

    INSPECTION END

    NO

    Replace malfunctioning heated oxygen sensor 2. Refer to Removal and Installation (bank 2) , Removal and Installation (bank 1) .

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