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Home >> Infiniti >> 2004 >> QX56 RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System >> DTC P0451: EVAP Control System Pressure Sensor >> Diagnostic Procedure
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Diagnostic Procedure

  1. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten ground three screws on the body.
      Fig 1: Locating Body Ground
      G02691460Courtesy of NISSAN MOTOR CO., U.S.A.

      Refer to GROUND INSPECTION .

    OK or NG

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR CONNECTOR FOR WATER 
    1. Disconnect EVAP control system pressure sensor harness connector.
      Fig 2: Locating EVAP Canister Vent Control Valve & EVAP Control System Pressure Sensor
      G02691461Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check sensor harness connector for water.

      Water should not exist. 

    OK or NG

    OK: GO TO 3.

    NG: Repair or replace harness connector.

  3. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR 

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 4.

    NG: Replace EVAP control system pressure sensor.

  4. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    For wiring diagram, refer to WIRING DIAGRAM .

    : INSPECTION END