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Home >> Nissan-Datsun >> 2019 >> Altima Edition ONE >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Control System (DTC/Circuit Diagnosis) (Pr25DD) (4 Of 4)) >> DTC/Circuit Diagnosis >> P2251 A/F Sensor >> DTC Diagnosis Procedure >> PR25DD engine

PR25DD engine

WARNING: This page is about a different variant/trim than selected.
  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

      F44

      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

      F44

      4

      F10

      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

      F44

      1

      F90

      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

      F44

      1

      Ground

      Not existed

      2

      ECM

      --

      Continuity

      Connector

      Terminal

      F90

      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 .

    INSPECTION END