Infiniti QX56 (Z62). Manual - part 592

EC-346

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0456 EVAP CONTROL SYSTEM

P0456 EVAP CONTROL SYSTEM

DTC Logic

INFOID:0000000006288325

DTC DETECTION LOGIC

This diagnosis detects leaks in the EVAP line between fuel tank and EVAP canister purge volume control sole-
noid valve, using the negative pressure caused by decrease of fuel temperature in the fuel tank after turning
ignition switch OFF.
If ECM judges there are no leaks, the diagnosis will be OK.

CAUTION:

• Use only a genuine NISSAN fuel filler cap as a replacement. If an incorrect fuel filler cap is used, the

MIL may illuminate.

• If the fuel filler cap is not tightened properly, the MIL may illuminate.
• Use only a genuine NISSAN rubber tube as a replacement.

DTC CONFIRMATION PROCEDURE

PBIB1026E

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0456

Evaporative emission control 

system leak

• EVAP system has a leak.
• EVAP system does not op-

erate properly.

• Incorrect fuel tank vacuum relief valve
• Incorrect fuel filler cap used
• Fuel filler cap remains open or does not close.
• Foreign matter caught in fuel filler cap.
• Leak is in line between intake manifold and EVAP canis-

ter purge volume control solenoid valve.

• Foreign matter caught in EVAP canister vent control 

valve.

• EVAP canister or fuel tank leaks
• EVAP purge line (pipe and rubber tube) leaks
• EVAP purge line rubber tube bent
• Loose or disconnected rubber tube
• EVAP canister vent control valve and the circuit
• EVAP canister purge volume control solenoid valve and 

the circuit

• Fuel tank temperature sensor
• O-ring of EVAP canister vent control valve is missing or 

damaged

• EVAP canister is saturated with water
• EVAP control system pressure sensor
• Refueling EVAP vapor cut valve
• ORVR system leaks
• Fuel level sensor and the circuit
• Foreign matter caught in EVAP canister purge volume 

control solenoid valve

P0456 EVAP CONTROL SYSTEM

EC-347

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

1.

PRECONDITIONING

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

Do you have CONSULT-III?

YES

>> GO TO 2.

NO

>> GO TO 4.

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

WITH CONSULT-III

1.

Turn ignition switch ON and select “EVAP DIAG READY” in “DATA MONITOR” mode with CONSULT-III.

2.

Start engine and wait at idle until “OFF” of “EVAP DIAG READY” changes to “ON”. 
NOTE:
It will take at most 2 hours until “OFF” of “EVAP DIAG READY” changes to “ON”.

3.

Turn ignition switch OFF and wait at least 90 minutes.
NOTE:
Never turn ignition switch ON during 90 minutes.

4.

Turn ignition switch ON and select “EVAP LEAK DIAG” in “DATA MONITOR” mode with CONSULT-III. 

5.

Check that “EVAP LEAK DIAG” indication.

Which is displayed on CONSULT-III?

CMPLT >> GO TO 3.
YET

>> Perform DTC CONFIRMATION PROCEDURE again. GO TO 1.

3.

PERFORM DTC CONFIRMATION PROCEDURE-II

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Proceed to

EC-347, "Diagnosis Procedure"

.

NO

>> INSPECTION END.

4.

PERFORM DTC CONFIRMATION PROCEDURE

WITH GST

1.

Start engine and wait engine idle for at least 2 hours. 

2.

Turn ignition switch OFF and wait at least 90 minutes.
NOTE:
Never turn ignition switch ON during 90 minutes.

3.

Turn ignition switch ON.

4.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Proceed to 

EC-347, "Diagnosis Procedure"

.

NO

>> INSPECTION END.

Diagnosis Procedure

INFOID:0000000006288326

1.

CHECK FUEL FILLER CAP DESIGN

1.

Turn ignition switch OFF.

2.

Check for genuine NISSAN fuel filler cap design.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Replace with genuine NISSAN fuel filler cap.

SEF915U

EC-348

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P0456 EVAP CONTROL SYSTEM

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 

EC-350, "Component Inspection (Fuel Filler Cap)"

.

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 

FL-12, "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.
• EVAP canister vent control valve is installed properly.

Refer to 

FL-10, "Exploded View"

.

• EVAP canister vent control valve.

Refer to 

EC-327, "Component Inspection (EVAP Canister Vent Control Valve)"

.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> Repair or replace EVAP canister vent control valve and O-ring. Refer to 

FL-10, "Exploded View"

.

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.

2.

Check if water will drain from the EVAP canister.

Does water drain from EVAP canister?

YES

>> GO TO 8.

NO-1

>> With CONSULT-III: GO TO 10.

NO-2

>> Without CONSULT-III: GO TO 11.

8.

CHECK EVAP CANISTER

Weigh the EVAP canister assembly with the EVAP canister vent control valve and EVAP control system pres-
sure sensor attached. Refer to 

FL-10, "Exploded View"

.

The weight should be less than 2.5 kg (5.5 lb).
Is the inspection result normal?

YES-1 >> With CONSULT-III: GO TO 10.
YES-2 >> Without CONSULT-III: GO TO 11.
NO

>> GO TO 9.

JSBIA0692ZZ

P0456 EVAP CONTROL SYSTEM

EC-349

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

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 

FL-10, "Hydraulic Layout"

.

10.

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 and let it idle.

3.

Select “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.

Is the inspection result normal?

YES

>> GO TO 13.

NO

>> GO TO 12.

11.

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.

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 

FL-10, "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 

EC-320, "Component Inspection (EVAP Canister Purge Volume Control Solenoid Valve)"

.

Is the inspection result normal?

YES

>> GO TO 14.

NO

>> Replace EVAP canister purge volume control solenoid valve. Refer to 

FL-10, "Exploded View"

.

14.

CHECK FUEL TANK TEMPERATURE SENSOR

Refer to 

EC-273, "Component Inspection (Fuel Tank Temperature Sensor)"

.

Is the inspection result normal?

YES

>> GO TO 15.

NO

>> Replace fuel level sensor unit. Refer to 

FL-5, "Removal and Installation"

.

15.

CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR

Refer to 

EC-335, "Component Inspection (EVAP Control System Pressure Sensor)"

.

Is the inspection result normal?

YES

>> GO TO 16.

Vacuum should exist.

Vacuum should exist.