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Home >> Infiniti >> 2023 >> QX80 Premium Select, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (DTCS) (3 Of 5) >> Engine (ECM) >> DTC P0456: EVAP Control System >> DTC Diagnosis Procedure
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DTC Diagnosis Procedure

  1. CHECK FUEL FILLER CAP DESIGN 
    1. Turn ignition switch OFF.
    2. Check for genuine NISSAN fuel filler cap design.
      GNSDB7259Courtesy of NISSAN NORTH AMERICA, INC.

    Is the inspection result normal?

    YES

    GO TO 2.

    NO

    Replace with genuine NISSAN fuel filler cap.

  2. CHECK FUEL FILLER CAP INSTALLATION 

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

    Is the inspection result normal?

    YES

    GO TO 3.

    NO

    Open fuel filler cap, then clean cap and fuel filler neck threads using air blower. Then retighten until reteaching sound is heard.

  3. CHECK FUEL FILLER CAP FUNCTION 

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

    Is the inspection result normal?

    YES

    GO TO 5.

    NO

    GO TO 4.

  4. CHECK FUEL TANK VACUUM RELIEF VALVE 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 5.

    NO

    Replace fuel filler cap with a genuine one.

  5. CHECK FOR EVAP LEAK 

    Refer to EVAP CANISTER : Inspection .

    Is there any leak in EVAP line?

    YES

    Repair or replace.

    NO

    GO TO 6.

  6. CHECK EVAP CANISTER VENT CONTROL VALVE 

    Check the following.

    Is the inspection result normal?

    YES

    GO TO 7.

    NO

    Repair or replace EVAP canister vent control valve and O-ring. Refer to EVAP CANISTER : Inspection .

  7. CHECK IF EVAP CANISTER SATURATED WITH WATER 
    1. Remove EVAP canister (1) with EVAP canister vent control valve (2) and EVAP control system pressure sensor attached.
      GNSDB21352Courtesy of NISSAN NORTH AMERICA, INC.
    2. Check if water will drain from the EVAP canister.

    Does water drain from EVAP canister?

    YES

    GO TO 8.

    NO

    With CONSULT: GO TO 10.

    NO

    Without CONSULT: GO TO 11.

  8. CHECK EVAP CANISTER 

    Weigh the EVAP canister assembly with the EVAP canister vent control valve and EVAP control system pressure sensor attached. Refer to EVAP CANISTER : Inspection .

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

    Is the inspection result normal?

    YES

    With CONSULT: GO TO 10.

    YES

    Without CONSULT: GO TO 11.

    NO

    GO TO 9.

  9. 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. Refer to EVAP CANISTER : Hydraulic Layout .

  10. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE OPERATION 

    SYMBOL WITH CONSULT

    1. Disconnect vacuum hose to EVAP canister purge volume control solenoid valve at EVAP service port.
    2. Start engine and let it idle.
    3. Select "PURG VOL CONT/V" in "ACTIVE TEST" mode.
    4. Touch "Qu" on CONSULT screen to increase "PURG VOL CONT/V" opening to 100%.
    5. Check vacuum hose for vacuum.

      Vacuum should exist.

    Is the inspection result normal?

    YES

    GO TO 13.

    NO

    GO TO 12.

  11. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE OPERATION 

    SYMBOL WITHOUT CONSULT

    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.

    Is the inspection result normal?

    YES

    GO TO 13.

    NO

    GO TO 12.

  12. CHECK VACUUM HOSE 

    Check vacuum hoses for clogging or disconnection. Refer to EVAP CANISTER : Hydraulic Layout .

    Is the inspection result normal?

    YES

    GO TO 13.

    NO

    Repair or reconnect the hose.

  13. CHECK EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 14.

    NO

    Replace EVAP canister purge volume control solenoid valve. Refer to EVAP CANISTER : Inspection .

  14. CHECK FUEL TANK TEMPERATURE SENSOR 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 15.

    NO

    Replace fuel level sensor unit. Refer to FUEL LEVEL SENSOR UNIT, FUEL FILTER AND FUEL PUMP ASSEMBLY : Removal & Installation .

  15. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 16.

    NO

    Replace EVAP control system pressure sensor. Refer to Component Inspection .

  16. CHECK EVAP PURGE LINE 

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

    Refer to EVAP CANISTER : Hydraulic Layout .

    Is the inspection result normal?

    YES

    GO TO 17.

    NO

    Repair or reconnect the hose.

  17. CLEAN EVAP PURGE LINE 

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

    GO TO 18.

  18. 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 EVAP CANISTER : Hydraulic Layout .

    Is the inspection result normal?

    YES

    GO TO 19.

    NO

    Repair or replace hoses and tubes.

  19. CHECK RECIRCULATION LINE 

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

    Is the inspection result normal?

    YES

    GO TO 20.

    NO

    Repair or replace hose, tube or fuel filler tube. Refer to FUEL TANK : Exploded View .

  20. CHECK REFUELING EVAP VAPOR CUT VALVE 

    Refer to Component Inspection .

    Is the inspection result normal?

    YES

    GO TO 21.

    NO

    Replace refueling EVAP vapor cut valve with fuel tank. Refer to EVAP CANISTER : Inspection .

  21. CHECK FUEL LEVEL SENSOR 

    Refer to Component Function Check .

    Is the inspection result normal?

    YES

    GO TO 22.

    NO

    Replace fuel level sensor unit. Refer to FUEL LEVEL SENSOR UNIT, FUEL FILTER AND FUEL PUMP ASSEMBLY : Removal & Installation .

  22. CHECK INTERMITTENT INCIDENT 

    Refer to Inspection .

    INSPECTION END

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