DTC Troubleshooting: P0456
DTC P0456: EVAP System Very Small Leak Detected
Special Tools Required
?Vacuum Pump/Gauge, 0?30 inHg Snap-on YA4000A or equivalent, commercially available
?Vacuum/Pressure Gauge, 0?4 inHg 07JAZ-001000B
The fuel system is designed to allow specified maximum vacuum and pressure conditions. Do not deviate from the vacuum and pressure tests as indicated in these procedures. Excessive pressure/vacuum would damage the EVAP components or cause eventual fuel tank failure.

NOTE:
Before you troubleshoot, review the general troubleshooting information.
Fresh fuel has a higher volatility that will create greater pressure/vacuum. The best condition for testing is less than a full tank of fresh fuel. If possible, to assist in leak detection, add 1 gallon of fresh fuel to the tank (as long as it will not fill the tank), just before starting these procedures.

DTC Description
Confirmed DTC
Pending DTC
P0456 EVAP System Very Small Leak Detected
    

1.
Problem verification:

Problem verification
?1.
Turn the vehicle to the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Select the EVAP TEST (ELCM) in the INSPECTION MENU, then select EVAP Leak Check Module Test with the HDS.

  

Is the result OK?

     
YES
     
     
     
If the test result is PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the EVAP leak check module, the EVAP canister purge valve, and the PCM. If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot. If the vehicle returns with the same DTC, continue with step 5.?
     
NO
     
     
     
The failure is duplicated. Go to step 2.
2.
EVAP canister vent hose check:

EVAP canister vent hose check
?1.
Check the EVAP canister drain hose (A) for a blockage or a restriction.


Is there a blockage or a restriction in the hose?

     
YES
     
     
     
Remove a blockage or a restriction, if needed, replace the EVAP canister drain hose.?
     
NO
     
     
     
Go to step 3.
3.
EVAP leak check module drain hose check:

EVAP leak check module drain hose check
?1.
Remove the EVAP canister filter, then check the blockage in the hoses and the EVAP canister filter.

Are the parts OK?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
Remove the blockage from them, or replace the part(s) if needed.?
4.
EVAP canister purge valve leak check:

EVAP canister purge valve leak check
?1.
Remove the EVAP canister purge valve with its connector and vacuum hose connected.

?2.
Disconnect the vacuum hose (purge line) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect the T-fitting (C), the vacuum gauge, and the vacuum pump/gauge, 0?30 inHg as shown.


?3.
Slowly apply about 2 kPa (0.6 inHg, 15 mmHg) of vacuum to the hose.

Does it hold vacuum for 1 minute?

     
YES
     
     
     
Leak not detected at the EVAP canister purge valve. Go to step 5.
     
NO
     
     
     
5.
Determine possible failure area (EVAP canister, others):

Determine possible failure area (EVAP canister, others)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the fuel vent tube (A) from the EVAP canister (B), and plug the EVAP canister port (C).


?3.
Remove the vacuum gauge and the tube joint adapter, and connect the vacuum pump/gauge (A) to the vacuum hose (purge line) (B) as shown.


?4.
Turn the vehicle to the ON mode.

?5.
Select the EVAP TEST (ELCM) in the INSPECTION MENU, then select CCV ON in the Single Solenoid Test with the HDS.

  

?6.
Apply vacuum to the hose until the Absolute Pressure of ELCM Pressure Sensor 2 kPa (0.6 inHg, 15 mmHg).
NOTE: Be careful not to exceed the vacuum. If you do, the EVAP leak check module can be damaged.

Signal
Current conditions
Values
Unit
Absolute Pressure of ELCM Pressure Sensor
    

?7.
Check the parameter(s) below with the HDS for 1 minute.
Signal
Current conditions
Values
Unit
Absolute Pressure of ELCM Pressure Sensor
    

Does it hold a vacuum?

     
YES
     
     
     
Go to step 7.
     
NO
     
     
     
Go to step 6.
6.
EVAP canister check:

EVAP canister check
?1.
Disconnect the EVAP canister drain hose (A) from the EVAP leak check module port (B), and plug it.


?2.
Connect the T-fitting (A), the vacuum gauge, and the vacuum pump/gauge, 0?30 inHg as shown.


?3.
Slow apply about 2 kPa (0.6 inHg, 15 mmHg) of vacuum to the hose.

Does the hose hold vacuum?

     
YES
     
     
     
The EVAP canister is OK. Replace the EVAP leak check module.?
     
NO
     
     
     
Check for a poor connection or damage to the EVAP purge line between the EVAP canister purge valve and the EVAP canister, then replace the EVAP canister.?
7.
Fuel fill pipe and fuel tank vapor recirculation tube visual check:

Fuel fill pipe and fuel tank vapor recirculation tube visual check
?1.
Check for a poor connection or damage to the fuel fill pipe and the fuel tank vapor recirculation tube.

Are the parts and connections OK?

     
YES
     
     
     
The fuel fill pipe and fuel tank vapor recirculation tube are OK. Go to step 8.
     
NO
     
     
     
8.
Shut-off valve check:

Shut-off valve check
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Check the flap of the shut-off valve (A).


Is the flap closed?

     
YES
     
     
     
Go to step 9.
     
NO
     
     
     
9.
Shut-off valve seal check:

Shut-off valve seal check
?1.
Check the flap seal of the shut-off valve (A) and the mating surface on the shut-off valve.


Is the flap seal missing or damaged, is the shut-off valve mating surface damaged?

     
YES
     
     
     
     
NO
     
     
     
The shut-off valve is OK. Check the fuel tank unit base gasket and fuel tank.?