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Home >> Infiniti >> 2009 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P0327 To P0850 >> DTC P0456: EVAP Control System >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK FUEL FILLER CAP DESIGN
    1. Turn ignition switch OFF.
    2. Check for genuine NISSAN fuel filler cap design.

      OK or NG 

      OK: GO TO 2.

      NG: Replace with genuine NISSAN fuel filler cap.

      Fig 1: Identifying Nissan Fuel Filler Cap
      G06315690Courtesy of NISSAN MOTOR CO., U.S.A.
  2. CHECK FUEL FILLER CAP INSTALLATION

    Check that the cap is tightened properly by rotating the cap clockwise.

    OK or NG 

    OK: GO TO 3.

    NG: Go to Next Step

    1. Open fuel filler cap, then clean cap and fuel filler neck threads using air blower.
    2. Retighten until ratcheting sound is heard.
  3. CHECK FUEL FILLER CAP FUNCTION

    Check for air releasing sound while opening the fuel filler cap.

    OK or NG 

    OK: GO TO  5.

    NG: GO TO 4.

  4. CHECK FUEL TANK VACUUM RELIEF VALVE

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 5.

    NG: Replace fuel filler cap with a genuine one.

  5. INSTALL THE PRESSURE PUMP

    To locate the EVAP leak, install EVAP service port adapter and pressure pump to EVAP service port securely.

    NOTE: Improper installation of the EVAP service port adapter to the EVAP service port may cause leaking.
    Fig 2: Identifying EVAP Service Port And EVAP Canister Purge Volume Control Solenoid Valve
    G06315691Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 3: Identifying Pressure Pump Connection With EVAP Service Port Adapter
    G06315692Courtesy of NISSAN MOTOR CO., U.S.A.

    With CONSULT-III: GO TO 6.

    Without CONSULT-III: GO TO  7.

  6. CHECK FOR EVAP LEAK

    With CONSULT-III 

    1. Turn ignition switch ON.
    2. Select "EVAP SYSTEM CLOSE" of "WORK SUPPORT" mode with CONSULT-III.
    3. Touch "START" and apply pressure into the EVAP line until the pressure indicator reaches the middle of the bar graph.
      CAUTION:
      • Do not use compressed air or a high pressure pump.
      • Do not exceed 4.12 kPa (0.042 kg/cm2 , 0.6 psi) of pressure in the system.
    4. Using EVAP leak detector, locate the EVAP leak. For the leak detector, refer to the instruction information for more details. Refer to "DESCRIPTION ".

      OK or NG 

      OK: GO TO  8.

      NG: Repair or replace.

      Fig 4: Identifying EVAP Leak Detector
      G06315693Courtesy of NISSAN MOTOR CO., U.S.A.
  7. CHECK FOR EVAP LEAK

    Without CONSULT-III 

    1. Turn ignition switch OFF.
    2. Apply 12 volts DC to EVAP canister vent control valve. The valve will close. (Continue to apply 12 volts until the end of test.)
      Fig 5: Identifying EVAP Canister Vent Control Valve And EVAP Control System Pressure Sensor
      G06315694Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Pressurize the EVAP line using pressure pump with 1.3 to 2.7 kPa (10 to 20 mmHg, 0.39 to 0.79 inHg), then remove pump and EVAP service port adapter.
      CAUTION:
      • Do not use compressed air or a high pressure pump.
      • Do not exceed 4.12 kPa (0.042 kg/cm2 , 0.6 psi) of pressure in the system.
    4. Using EVAP leak detector, locate the EVAP leak. For the leak detector, refer to the instruction information for more details. Refer to "DESCRIPTION ".

      OK or NG 

      OK: GO TO 8.

      NG: Repair or replace.

      Fig 6: Identifying EVAP Leak Detector
      G06315695Courtesy of NISSAN MOTOR CO., U.S.A.
  8. CHECK EVAP CANISTER VENT CONTROL VALVE

    Check the following.

    • EVAP canister vent control valve is installed properly.

      Refer to "REMOVAL AND INSTALLATION ".

    • EVAP canister vent control valve.

      Refer to "COMPONENT INSPECTION ".

      OK or NG 

      OK: GO TO 9.

      NG: Repair or replace EVAP canister vent control valve and O-ring.

  9. CHECK IF EVAP CANISTER SATURATED WITH WATER
    1. Remove EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor attached.
    2. Does water drain from the EVAP canister?

      Yes or No 

      YES: GO TO 10.

      No (With CONSULT-III): GO TO  12.

      No (Without CONSULT-III): GO TO  13.

      Fig 7: Checking EVAP Canister Saturated With Water
      G06315696Courtesy of NISSAN MOTOR CO., U.S.A.
  10. CHECK EVAP CANISTER

    Weigh the EVAP canister with the EVAP canister vent control valve and EVAP control system pressure sensor attached.

    The weight should be less than 2.5 kg (5.5 lb). 

    OK or NG 

    OK (With CONSULT-III): GO TO  12.

    OK (Without CONSULT-III): GO TO  13.

    NG: GO TO 11.

  11. DETECT MALFUNCTIONING PART

    Check the following.

    • EVAP canister for damage
    • EVAP hose between EVAP canister and vehicle frame for clogging or poor connection

      Repair hose or replace EVAP canister.

  12. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE OPERATION

    With CONSULT-III 

    1. Disconnect vacuum hose to EVAP canister purge volume control solenoid valve at EVAP service port.
    2. Start engine.
    3. Perform "PURG VOL CONT/V" in "ACTIVE TEST" mode.
    4. Touch "Qu" on CONSULT-III screen to increase "PURG VOL CONT/V" opening to 100%.
    5. Check vacuum hose for vacuum when revving engine up to 2, 000 RPM.

      Vacuum should exist. 

      OK or NG 

      OK: GO TO  15.

      NG: GO TO  14.

  13. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE OPERATION

    Without CONSULT-III 

    1. Start engine and warm it up to normal operating temperature.
    2. Stop engine.
    3. Disconnect vacuum hose to EVAP canister purge volume control solenoid valve at EVAP service port.
    4. Start engine and let it idle for at least 80 seconds.
    5. Check vacuum hose for vacuum when revving engine up to 2, 000 RPM.

      Vacuum should exist. 

      OK or NG 

      OK: GO TO  16.

      NG: GO TO 14.

  14. CHECK VACUUM HOSE

    Check vacuum hoses for clogging or disconnection. Refer to "DESCRIPTION ".

    OK or NG 

    OK: GO TO 15.

    NG: Repair or reconnect the hose.

  15. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 16.

    NG: Replace EVAP canister purge volume control solenoid valve.

  16. CHECK FUEL TANK TEMPERATURE SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 17.

    NG: Replace fuel level sensor unit.

  17. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 18.

    NG: Replace EVAP control system pressure sensor.

  18. CHECK EVAP PURGE LINE

    Check EVAP purge line (pipe, rubber tube, fuel tank and EVAP canister) for cracks or improper connection.

    Refer to "DESCRIPTION ".

    OK or NG 

    OK: GO TO 19.

    NG: Repair or reconnect the hose.

  19. CLEAN EVAP PURGE LINE

    Clean EVAP purge line (pipe and rubber tube) using air blower.

    GO TO 20.

  20. CHECK EVAP/ORVR LINE

    Check EVAP/ORVR line between EVAP canister and fuel tank for clogging, kink, looseness and improper connection.

    For location, refer to ON BOARD REFUELING VAPOR RECOVERY (ORVR) .

    OK or NG 

    OK: GO TO 21.

    NG: Repair or replace hoses and tubes.

  21. CHECK RECIRCULATION LINE

    Check recirculation line between filler neck tube and fuel tank for clogging, kink, cracks, looseness and improper connection.

    OK or NG 

    OK: GO TO 22.

    NG: Repair or replace hose, tube or filler neck tube.

  22. CHECK REFUELING EVAP VAPOR CUT VALVE

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 23.

    NG: Replace refueling EVAP vapor cut valve with fuel tank.

  23. CHECK FUEL LEVEL SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO 24.

    NG: Replace fuel level sensor unit.

  24. CHECK INTERMITTENT INCIDENT

    Refer to "HOW TO CHECK TERMINAL "and "INTERMITTENT INCIDENT ".

    INSPECTION END