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, record all freeze data and any on-board snapshot, and 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
Freeze Frame
P0456 EVAP System Vary Small Leak Detected
      

1.
Fuel fill cap installation check:

Fuel fill cap installation check
?1.
Check the fuel fill cap (the cap must say TIGHTEN TO CLICK). It should turn 1/4 turn after it's tight, then it clicks.

Is the correct fuel fill cap installed and properly tightened?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Replace the fuel fill cap or tighten the cap, then do the repair verification.
2.
Fuel fill cap seal and fuel fill pipe mating surface check:

Fuel fill cap seal and fuel fill pipe mating surface check
?1.
Check the fuel fill cap seal (A) and the fuel fill pipe mating surface (B). Verify that the fuel fill cap tether cord (C) is not caught under the cap.


Is the fuel fill cap seal missing or damaged, is the fuel fill pipe damaged, or is the tether cord caught under the cap?

     
YES
     
     
     
Replace the fuel fill cap or tighten the cap, replace the fuel fill pipe if damaged, then do the repair verification.
     
NO
     
     
     
The fuel fill cap and the fuel fill pipe are OK. Go to step 3.
3.
Fuel tank vapor recirculation tube visual check:

Fuel tank vapor recirculation tube visual check
?1.
Press the engine start/stop button to select the OFF mode.

?2.
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
     
     
     
Replace the fuel tank vapor recirculation tube, or replace the fuel tank if needed, then do the repair verification.
4.
EVAP canister purge valve leak check:

EVAP canister purge valve leak check
?1.
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.


?2.
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.
Problem verification:

Problem verification
?1.
Press the engine start/stop button to select 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 vehicle returns with the same DTC, continue with step 6.
     
NO
     
     
     
The failure is duplicated. Go to step 6.
6.
Determine possible failure area (EVAP canister vent shut valve, others):

Determine possible failure area (EVAP canister vent shut valve, others)
?1.
Press the engine start/stop button to select the OFF mode.

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


?3.
Remove the T-fitting and vacuum pump/gauge, then connect the vacuum pump/gauge to the vacuum hose (A) as shown.


?4.
Press the engine start/stop button to select 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 7.
     
NO
     
     
     
Go to step 9.
7.
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 fresh air hose (A) from the EVAP canister (B), and plug the EVAP canister vent shut valve port (C).


?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 8.
     
NO
     
     
     
8.
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, then do the repair verification.
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 canister, then do the repair verification.
9.
Fuel fill pipe and fuel vapor return pipe visual check:

Fuel fill pipe and fuel vapor return pipe 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 vapor return pipe.

Are the parts OK?

     
YES
     
     
     
The fuel fill pipe and the fuel vapor return pipe are OK. Check the fuel tank unit base gasket and the fuel tank, then do the repair verification.
     
NO
     
     
     
Repair or replace the damaged parts, then do the repair verification.
Repair verification:

?1.
Press the engine start/stop button to select the OFF mode.

?2.
Install the parts in the reverse order of removal.

?3.
Press the engine start/stop button to select the ON mode.

?4.
Reset the PCM with the HDS.


?5.
Do the PCM idle learn procedure.

?6.
Select the EVAP TEST in the INSPECTION MENU, then select the FUNCTION TEST with the HDS.

  

Is the result OK?

     
YES
     
     
     
Troubleshooting is complete.?
     
NO
     
     
     
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, then go to step 1.