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Home >> Infiniti >> 2021 >> QX80 Premium Select, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (5 Of 5) >> Engine (ECM) >> DTC P2A01: O2 Sensor 2 Bank 1 >> DTC Diagnosis Procedure
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DTC 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 8.

  2. CHECK HEATED OXYGEN SENSOR 2 CONNECTOR 
    1. Disconnect heated oxygen sensor 2 (HO2S2) 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 FOR OPEN AND SHORT 
    1. Disconnect ECM harness connector.
    2. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2

      ECM

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      1

      F131

      1

      F91

      43

      Existed
    3. 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 FOR OPEN AND SHORT 
    1. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2

      ECM

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      1

      F131

      2

      F92

      84

      Existed
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.

      HO2S2

      ECM

      Ground

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      1

      F131

      2

      F92

      84

      Ground

      Not existed
    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 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 7.

    NO

    GO TO 6.

  6. REPLACE HEATED OXYGEN SENSOR 2 

    Replace malfunctioning heated oxygen sensor 2. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST : 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 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

  7. CHECK INTERMITTENT INCIDENT 

    Refer to Inspection .

    INSPECTION END

  8. CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE 
    1. Clear the mixture ratio self-learning value. Refer to Work Procedure .
    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 9.

  9. CHECK HEATED OXYGEN SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect heated oxygen sensor 2 (HO2S2) harness connector.
    3. Disconnect ECM harness connector.
    4. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2

      ECM

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      1

      F131

      1

      F91

      43

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

    Is the inspection result normal?

    YES

    GO TO 10.

    NO

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

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

      HO2S2

      ECM

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      1

      F131

      2

      F92

      84

      Existed
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.

      HO2S2

      ECM

      Ground

      Continuity

      Bank

      Connector

      Terminal

      Connector

      Terminal

      1

      F131

      2

      F92

      84

      Ground

      Not existed
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES

    GO TO 11.

    NO

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

  11. CHECK HEATED OXYGEN SENSOR 2 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 13.

    NO

    GO TO 12.

  12. REPLACE HEATED OXYGEN SENSOR 2 

    Replace malfunctioning heated oxygen sensor 2. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST : 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 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

  13. CHECK INTERMITTENT INCIDENT 

    Refer to Inspection .

    INSPECTION END

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