DTC Troubleshooting: P2421
DTC P2421: EVAP Canister Vent Shut Valve Stuck Open
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
P2421 EVAP Canister Vent Shut Valve Stuck Open
    

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 in the INSPECTION MENU, then select the FUNCTION TEST with the HDS.

  

Is the result OK?

     
YES
     
     
     
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the FTP sensor, the EVAP canister purge valve, the EVAP canister vent shut 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 2.?
     
NO
     
     
     
The failure is duplicated. Go to step 2.
2.
EVAP canister vent hose check:

EVAP canister vent hose check
?1.
Remove the right front floor undercover.

?2.
Check the EVAP canister vent 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 vent hose.?
     
NO
     
     
     
Go to step 3.
3.
Fuel tank vapor recirculation tube visual check:

Fuel tank vapor recirculation tube visual check
?1.
Check for a poor connection or damage at the fuel tank vapor recirculation tube.

Is the tube OK?

     
YES
     
     
     
The tube is OK. Go to step 4.
     
NO
     
     
     
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 a T-fitting (C), a vacuum gauge, and a vacuum pump/gauge, 0?30 inHg, to the vacuum hose 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 vent shut valve, others):

Determine possible failure area (EVAP canister vent shut valve, 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 T-fitting and vacuum pump/gauge, 0?30 inHg, and connect the vacuum pump/gauge, 0?30 inHg to the vacuum hose (purge line) (A) as shown.


?4.
Turn the vehicle to the ON mode.

?5.
Select the EVAP TEST in the INSPECTION MENU, then select EVAP CVS ON in the SINGLE SOLENOID with the HDS.

  

?6.
Apply vacuum to the hose until the FTP reads 1.90 V (-0.59 inHg, -15.1 mmHg).
NOTE: Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.

Signal
Current conditions
Values
Unit
FTP SENSOR
    

?7.
Check the parameter(s) below with the HDS for 1 minute.
Signal
Current conditions
Values
Unit
FTP SENSOR
    

Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?

     
YES
     
     
     
Go to step 6.
     
NO
     
     
     
Go to step 8.
6.
EVAP canister vent shut valve operation check:

EVAP canister vent shut valve operation check
?1.
Select the EVAP TEST in the INSPECTION MENU, then select EVAP CVS OFF in the SINGLE SOLENOID with the HDS.

  

?2.
Disconnect the EVAP canister vent hose (A) from the EVAP canister vent shut valve port (B), and plug it.


?3.
Apply vacuum to the hose until the FTP reads 1.90 V (-0.59 inHg, -15.1 mmHg).
NOTE: Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.

Signal
Current conditions
Values
Unit
FTP SENSOR
    

?4.
Check the parameter(s) below with the HDS for 1 minute.
Signal
Current conditions
Values
Unit
FTP SENSOR
    

Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?

     
YES
     
     
     
The EVAP canister vent shut valve is OK. Go to step 7.
     
NO
     
     
     
7.
EVAP canister purge line visual check:

EVAP canister purge line visual check
?1.
Check for a poor connection or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve. Also check for damage to the EVAP canister.

Are the line and the EVAP canister OK?

     
YES
     
     
     
Replace these parts.?
FTP sensor O-ring
EVAP canister vent shut valve case and O-ring
EVAP canister
     
NO
     
     
     
Replace or repair the EVAP canister purge line or the canister.?
8.
Fuel fill pipe and fuel tank vapor recirculation tube visual check:

Fuel fill pipe and fuel tank vapor recirculation tube visual check
?1.
Select EVAP CVS OFF in the SINGLE SOLENOID with the HDS.

  

?2.
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 the fuel tank vapor recirculation tube are OK. Go to step 9.
     
NO
     
     
     
9.
Shut-off valve check:

Shut-off valve check
?1.
Remove the mis-fuel inhibit device.

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


Is the flap closed?

     
YES
     
     
     
Go to step 10.
     
NO
     
     
     
10.
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
     
     
     
Check the fuel tank unit O-ring and the fuel tank.?