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DTC Troubleshooting




Control System DTCs

DTC Troubleshooting: P0456

DTC P0455 : EVAP System Large Leak Detected
DTC P0456 : EVAP System Very Small Leak Detected

Special Tools Required

Vacuum Pump/Gauge, 0-30 inHg Snap-on YA4000A or equivalent, commercially available
NOTICE:
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 How To Troubleshoot The Fuel And Emissions Systems.
* 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.

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 the fuel fill pipe, then do the repair verification.
-NO- The fuel fill cap and the fuel fill pipe are OK. Go to step 3.

3. Problem verification:

Problem verification
-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

-3. Do the EVAP 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 ECM.
-NO- The failure is duplicated. Go to step 4.

4. Fuel tank vapor recirculation tube visual check:

Fuel tank vapor recirculation tube visual check
-1. Turn the ignition switch to LOCK (0).

-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 5.
-NO- Replace the fuel tank vapor recirculation tube, or replace the fuel tank Removal and Replacement if needed, then do the repair verification.

5. Determine possible failure area (EVAP canister vent shut valve, others):

Determine possible failure area (EVAP canister vent shut valve, others)
-1. Disconnect the fuel tank vapor control valve hose (A) and the fresh air hose (B) from the EVAP canister (C), and plug the EVAP canister ports (D).





-2. Disconnect the vacuum hose (engine side) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect a vacuum pump/gauge, 0-30 inHg, to the purge valve as shown.





-3. Turn the ignition switch to ON (II).

-4. Select EVAP PCS ON in the INSPECTION MENU with the HDS.

-5. 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.

-6. Select EVAP PCS OFF in the INSPECTION MENU with the HDS.

-7. Monitor the FTP SENSOR in the DATA LIST for 1 minute with the HDS.

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 purge line leak check:

EVAP canister purge line leak check
-1. Reconnect the vacuum hose (A) (engine side) to the EVAP canister purge valve.





-2. Disconnect the vacuum hose (EVAP canister side) (B) from the EVAP canister purge valve (C) in the engine compartment, then connect the vacuum pump/gauge to the purge valve as shown.

-3. Turn the ignition switch to ON (II).

-4. 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.

-5. Monitor the FTP SENSOR in the DATA LIST for 1 minute with the HDS.

Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?
-YES- Go to step 7.
-NO- The EVAP canister purge line is OK. Replace the EVAP canister purge valve Service and Repair, then do the repair verification.

7. EVAP canister purge line visual check:

EVAP canister purge line visual check
-1. Check for a loose or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve. Also check for a leaking EVAP canister.

Are the line and the 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- Reconnect or repair the EVAP canister purge line, then do the repair verification.

8. EVAP canister vent shut valve operation check:

EVAP canister vent shut valve operation check
-1. Reconnect the fresh air hose (A) from the EVAP canister (B).





-2. Reconnect the vacuum hose (engine side) to the EVAP canister purge valve.

-3. Disconnect the vacuum hose (EVAP canister side) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect the vacuum pump/gauge to the purge valve as shown.





-4. Select EVAP CVS ON in the INSPECTION MENU with the HDS.

-5. 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.

-6. Monitor the FTP SENSOR in the DATA LIST for 1 minute with the HDS.

Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?
-YES- Replace the EVAP canister vent shut valve Service and Repair, then do the repair verification.
-NO- The EVAP canister vent shut valve is OK. Go to step 9.

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 INSPECTION MENU with the HDS.

-2. Check for looseness or damage at the fuel fill pipe and the fuel vapor return pipe.

Are the parts OK?
-YES- The fuel fill pipe and 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. Turn the ignition switch to LOCK (0).

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

-3. Turn the ignition switch to ON (II).

-4. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-5. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure.

-6. Do the EVAP 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 ECM, then go to step 1.
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