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DTC Troubleshooting




DTC Troubleshooting: P0455, P0456

DTC P0455:

EVAP System Large Leak Detected

DTC P0456:

EVAP System Very Small Leak Detected

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.


Special Tools Required

- Vacuum Pump/Gauge, 0-30 inHg Snap-on YA4000A or equivalent, commercially available

NOTE:

- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.
- Fresh fuel has a higher volatility that creates 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. 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 or tighten the cap, then go to step 29.

2. Check the fuel fill cap seal (A) and the fuel fill pipe mating surface (B). Make sure 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 go to step 29.

NO -

Go to step 3.

3. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

4. Clear the DTC with the HDS.

5. Do the EVAP FUNCTION TEST in the INSPECTION MENU 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, or the EVAP canister vent shut valve, and the PCM.

NO -

Go to step 6.

6. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

7. Check for a poor connection or damage at the fuel tank vapor recirculation tube.

Is the tube OK?

YES -

Go to step 8.

NO -

- Reconnect or replace the fuel tank vapor recirculation tube, then go to step 28.
- If needed, replace the fuel tank Removal and Replacement, then go to step 28.

8. Disconnect the fuel tank vapor recirculation tube (A) and the fresh air hose (B) from the EVAP canister (C), then plug the EVAP canister ports (D).






9. 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.





10. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

11. Select EVAP PCS ON in the INSPECTION MENU with the HDS.

12. 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 specified vacuum. If you do, the FTP sensor can be damaged.

13. Select EVAP PCS OFF in the INSPECTION MENU with the HDS, then remove the vacuum pump from the purge valve.

14. Monitor the FTP SENSOR in the DATA LIST for 1 minute with the HDS, then remove the vacuum pump from the purge valve.

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

YES -

Go to step 15.

NO -

Go to step 20.

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

16. 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 vacuum hose as shown.





17. 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 specified vacuum. If you do, the FTP sensor can be damaged.

18. 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 19.

NO -

Replace the EVAP canister purge valve Service and Repair, then go to step 28.

19. 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 go to step 28:

- 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 go to step 28.

20. Reconnect the fresh air hose (A) to the EVAP canister (B).





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

22. 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.





23. Select EVAP CVS ON in the INSPECTION MENU with the HDS.

24. Apply vacuum to the EVAP system until the FTP reads 1.90 V (-0.59 inHg, -15.1 mmHg).

NOTE: Be careful not to exceed the specified vacuum. If you do, the FTP sensor can be damaged.

25. 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 go to step 28.

NO -

Go to step 26.

26. Select EVAP CVS OFF in the INSPECTION MENU with the HDS.

27. Check these parts for looseness or damage:

- Fuel fill pipe
- Fuel vapor return pipe

Are the parts OK?

YES -

Check the fuel tank unit base gasket Fuel Tank Unit Removal/Installation and the fuel tank, then go to step 28.

NO -

Repair or replace the damaged parts, then go to step 28.

28. Reconnect all hoses and connectors.

29. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

30. Reset the PCM with the HDS.

31. Do the PCM idle learn procedure PCM Idle Learn Procedure.

32. Do the EVAP FUNCTION TEST in the INSPECTION MENU 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.

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