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Home >> Infiniti >> 2024 >> Q50 Sensory, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (7 Of 7) >> Engine (ECM) >> P2270 O2 Sensor >> 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 9.

  2. CHECK GROUND CONNECTION 
    1. Turn ignition switch OFF.
    2. Check ground connection E191. Refer to Ground Inspection in 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.
      HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      1 F125 4 F143 81 Existed
    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 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 F125 3 F143 49 Existed
    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.
      HO2S2 Ground Continuity
      Bank Connector Terminal
      1 F125 3 Ground Not existed
      ECM Ground Continuity
      Bank Connector Terminal
      1 F143 49 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 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 heated 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 Inspection .

    >>

    INSPECTION END

  9. CHECK GROUND CONNECTION 
    1. Turn ignition switch OFF.
    2. Check ground connection E191. Refer to Ground Inspection in 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 Work Procedure .
    2. Run engine for at least 10 minutes at idle speed.

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

    YES>>

    Perform trouble diagnosis for DTC P0172. Refer to DTC Description .

    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.
      HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      1 F125 4 F143 81 Existed
    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, 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.
      HO2S2 ECM Continuity
      Bank Connector Terminal Connector Terminal
      1 F125 3 F143 49 Existed
    2. Check the continuity between HO2S2 harness connector or ECM harness connector and ground.
      HO2S2 Ground Continuity
      Bank Connector Terminal
      1 F125 3 Ground Not existed
      ECM Ground Continuity
      Bank Connector Terminal
      1 F143 49 Ground Not existed
    3. Also check harness for short to power.

    Is the inspection result normal?

    YES>>

    GO TO 13.

    NO>>

    Repair open circuit, 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>>

    INSPECTION END

    NO>>

    Replace malfunctioning heated oxygen sensor 2. Refer to CATALYST : Exploded View .

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