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 will damage the EVAP components or eventually cause fuel tank failure.
Special Tools Required
- Vacuum/Pressure Gauge, 0-4 inHg 07JAZ-001000B
- 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 24.
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 24.
NO -
Go to step 3.
3. Turn the ignition switch to ON (II).
4. Clear the DTC with the HDS.
5. Turn the ignition switch to LOCK (0).
6. Check for a poor connection or damage at the fuel tank vapor recirculation tube.
Is the tube OK?
YES -
Go to step 7.
NO -
- Reconnect or replace the fuel tank vapor recirculation tube, then go to step 26.
- If needed, replace the fuel tank Removal and Replacement, then go to step 26.
7. 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 in.Hg, to the EVAP canister purge valve as shown.
8. Slowly apply about 2 kPa (0.6 in Hg, 15 mmHg) of vacuum to the hose.
Does it hold vacuum for 1 minute?
YES -
Go to step 9.
NO -
Replace the EVAP canister purge valve, then go to step 25.
9. Turn the ignition switch to ON (II).
10. 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 5.
11. Turn the ignition switch to LOCK (0).
12. Disconnect the fuel tank vapor recirculation tube (A) from the EVAP canister (B), and plug the EVAP canister port (C).
13. Remove the vacuum gauge, then connect the vacuum pump/gauge to the vacuum hose (A) as shown.
14. Turn the ignition switch to ON (II).
15. Select EVAP CVS ON in the INSPECTION MENU with the HDS.
16. Apply vacuum to the hose until the FTP reads 1.90 V (-0.59 in Hg, -15.1 mmHg).
NOTE: Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.
17. 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 in Hg,0.5 mmHg)?
YES -
Go to step 18.
NO -
Go to step 23.
18. Select EVAP CVS OFF in the INSPECTION MENU with the HDS.
19. Disconnect the fresh air hose (A) from the EVAP canister vent shut valve (B), and plug the EVAP canister vent shut valve port (C).
20. Apply vacuum to the EVAP system until the FTP reads 1.90 V (-0.59 in Hg, -15.1 mmHg).
NOTE: Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.
21. 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 in Hg,2.5 mmHg)?
YES -
Go to step 22.
NO -
Replace the EVAP canister vent shut valve, then go to step 25.
22. Check for a loose or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve, or a leaking EVAP canister purge valve.
Are the line and the EVAP canister purge valve OK?
YES -
Replace these parts, then go to step 25:
- 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 25.
23. Select EVAP CVS OFF in the INSPECTION MENU with the HDS.
24. 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 check the fuel tank, then go to step 25.
NO -
Repair or replace the damaged parts, then go to step 25.
25. Reconnect all hoses and connectors.
26. Turn the ignition switch to ON (II).
27. Reset the ECM/PCM with the HDS.
28. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.
29. 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.