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Home >> Infiniti >> 2023 >> QX50 Pure, FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTC/Circuit Diagnosis) (4 Of 4) >> DTC/Circuit Diagnosis >> DTC P2239: O2 Sensor Bank 1 Sensor 1 >> Diagnosis Procedure

Diagnosis Procedure

  1. CHECK AIR FUEL RATIO SENSOR 1 POWER SUPPLY 
    1. Turn ignition switch OFF.
    2. Disconnect air fuel ratio (A/F) sensor 1 harness connector.
    3. Turn ignition switch ON.
    4. Check the voltage between A/F sensor 1 harness connector and ground.
      + - Voltage
      A/F sensor 1
      Connector Terminal
      F18 4 Ground Battery voltage

    Is the inspection result normal?

    YES>>

    GO TO 3.

    NO>>

    GO TO 2.

  2. CHECK AIR FUEL RATIO SENSOR 1 POWER SUPPLY CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect IPDM E/R harness connector.
    3. Check the continuity between A/F sensor 1 harness connector and IPDM E/R harness connector.
      A/F sensor 1 IPDM E/R Continuity
      Connector Terminal Connector Terminal
      F18 4 E115 75 Existed
    4. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES>>

    Perform trouble diagnosis for power supply circuit.

    NO>>

    Repair or replace malfunctioning part.

  3. CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.
      A/F sensor 1 ECM Continuity
      Connector Terminal Connector Terminal
      F18 1 F52 86 Existed
      2 88
    4. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.
      A/F sensor 1 - Continuity
      Connector Terminal
      F18 1 Ground Not existed
      2
      ECM - Continuity
      Connector Terminal
      F52 86 Ground Not existed
      88
    5. Also check harness for short to ground and short to power.

    Is the inspection result normal?

    YES>>

    GO TO 4.

    NO>>

    Repair or replace malfunctioning part.

  4. REPLACE A/F SENSOR 1 

    Replace malfunctioning A/F sensor 1. Refer to Exploded View .

    CAUTION:
    • Discard any A/F 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 A/F sensor, clean exhaust system threads.

    >>

    INSPECTION END