DTC Troubleshooting
DTC Troubleshooting: P0455, P0456, 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 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 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. 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 23.
2. 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 go to step 30.
NO -
Go to step 3.
3. Turn the ignition switch to ON (II).
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, the EVAP canister vent shut valve, and the ECM/PCM.�
NO -
Go to step 6.
6. Turn the ignition switch to LOCK (0).
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 -
- Replace the fuel tank vapor recirculation tube, then go to step 30.
- If needed, replace the fuel tank Service and Repair, then go to step 30.
8. Disconnect the fuel tank vapor recirculation tube (A) and the fresh air hose (B) from the EVAP canister (C), and plug the EVAP canister ports (D).
9. Remove the EVAP canister purge valve (A) from the throttle body (B) without disconnecting the vacuum hose (C) or the EVAP canister purge valve 2P connector (D) Service and Repair, then connect a vacuum pump/gauge, 0-30 inHg, to the purge valve as shown.
10. Turn the ignition switch to ON (II).
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 vacuum. If you do, the FTP sensor can be damaged.
13. Select EVAP PCS OFF in the INSPECTION MENU with the HDS and disconnect the vacuum pump/gauge.
14. 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 15.
NO -
Go to step 21.
15. Turn the ignition switch to LOCK (0).
16. Reinstall the EVAP canister purge valve (A) to the throttle body (B) with a new O-ring, and disconnect the vacuum hose (EVAP canister side) (C) from the EVAP canister purge valve, then connect the vacuum pump/gauge to the vacuum hose as shown.
17. Turn the ignition switch to ON.
18. 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.
19. 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 20.
NO -
Replace the EVAP canister purge valve Service and Repair, then go to step 30.
20. Check for a loose or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve, or check for a leaking the EVAP canister.
Are the line and the EVAP canister OK?
YES -
Replace these parts, then go to step 30:
- FTP sensor O-ring
- EVAP canister vent shut valve case and O-ring
- EVAP canister
NO -
Reconnect or repair the EVAP canister purge hose, then go to step 30.
21. Turn the ignition switch to LOCK (0).
22. Reconnect the fresh air hose (A) to the EVAP canister (B).
23. Remove the EVAP canister purge valve (A) from the throttle body (B) without disconnecting the vacuum hose (C) or the EVAP canister purge valve 2P connector (D) Service and Repair, then connect the vacuum pump/gauge to the purge valve as shown.
24. Turn the ignition switch to ON (II).
25. Select EVAP CVS ON in the INSPECTION MENU with the HDS.
26. 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 vacuum. If you do, the FTP sensor can be damaged.
27. 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 30.
NO -
Go to step 28.
28. Select EVAP CVS OFF in the INSPECTION MENU with the HDS.
29. 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, and check the fuel tank, then go to step 30.
NO -
Repair or replace the damaged part(s), then go to step 30.
30. Reconnect all hoses and connectors.
NOTE: When you install the EVAP canister purge valve to the throttle body, use a new O-ring.
31. Turn the ignition switch to ON (II).
32. Reset the ECM/PCM with the HDS.
33. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.
34. 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 ECM/PCM, then go to step 1.