P0456 diagnostic code

[MrPotter]

I have a 2006 honda civic EX with 37000 miles and I have the "check gas cap" message on. I had auto zone put the code reader on and it comes up with code P0456. I have made sure the gas cap is on tight and I did that several days ago and the message remains. I do not have a check engine light. is there a way to reset this message without having to use a code reader? and what is the most probable cause of this message besides the gas cap? any information will be greatly appreciated.

[solidust]

take of the neg. on the battery wait 30 sec. and then put it back on and make sure the gas cap is tight after that..then there should be no code

[illusionstwice]

You can start by searching:
"Check Fuel Cap" - Merged Threads

It happens sometimes. As long as your cap is locked, your fine. Mine went away after a day.

welcome to the site

[jasonandre]

DTC P0456: EVAP System Very Small Leak Detected

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 22.


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 22.

NO - Go to step 3.


3. Turn the ignition switch 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, or the EVAP canister vent shut valve and the ECM/PCM.■

NO - Go to step 6.

6. Turn the ignition switch OFF.

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 22.

If necessary, replace the fuel tank, then go to step 22.

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

9. Disconnect the vacuum hose (purge line) (A) from the EVAP canister purge valve (B) in the engine compartment, and connect a vacuum pump/gauge, 0-30 in.Hg, to the vacuum hose as shown.

10. Turn the ignition switch ON (II).

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

12. 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.

13. 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 14.

NO - Go to step 19.

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

15. Disconnect the fresh air hose (A) from the EVAP canister (B), and plug the EVAP canister port (C).

16. 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.

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, 2.5 mmHg)?

YES - Go to step 18.

NO - Replace the EVAP canister vent shut valve, then go to step 21.

18. Check for a loose or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve. Is the line OK?

YES - Replace these parts, then go to step 21:

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 21.

21. Reconnect all hoses and connectors.

22. Turn the ignition switch ON (II).

23. Reset the ECM/PCM with the HDS.

24. Do the ECM/PCM idle learn procedure.

25. 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.