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Home >> Nissan-Datsun >> 2005 >> X-Trail LE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS U1000 To P0139 >> DTC P0138 Ho2S2 >> Diagnostic Procedure

Diagnostic Procedure

  1. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten ground three screws on the body.

      Refer to "GROUND INSPECTION ".

    Fig 1: Identifying Multi-Remote Control Unit And Steering Member
    G06152373Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Disconnect heated oxygen sensor 2 harness connector.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between HO2S2 terminal 3 and ECM terminal 78.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    4. Also check harness for short to ground and short to power.
    Fig 2: Identifying Heated Oxygen Sensor 1 Harness Connector
    G06152492Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 3.

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

  3. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between HO2S2 terminal 2 ECM terminal 74.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    2. Check harness continuity between ECM terminal 74 or HO2S2 terminal 2 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should not exist. 

    3. Also check harness for short to power.

    OK or NG 

    OK: GO TO 4.

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

  4. CHECK HO2S2 CONNECTOR FOR WATER 

    Check heated oxygen sensor 2 for water.

    Water should not exist. 

    OK or NG 

    OK: GO TO 5.

    NG: Repair or replace harness or connectors.

  5. CHECK HEATED OXYGEN SENSOR 2 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 6.

    NG: Replace heated oxygen sensor 2.

  6. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    INSPECTION END