P0456 Small evap leak typically happens when tank about half full

mookieit · Jul 17, 2023

Been having p0456 small evap leak code for a few years now.

I erase the code every time it happens.

Noticed that the code typically happens when the gas tank reaches about half empty after gas fill up.

Changed recently the purge valve and treated the gas cap with WD40 silicone.

Has anyone experienced the same? How did they resolve it?

Or please share what else could I check?

Rapid Red · Jul 17, 2023

Have you replaced the cap ?

mookieit · Jul 17, 2023

Rapid Red said:
Have you replaced the cap ?

No, you mean replace the gas cap?

Southview · Jul 17, 2023

There is another flap about 5” down the filler neck. That is the one that gets build up. Use a long screwdriver to open the first flap so you can get to the 2nd one to clean. Use a flashlight. You’ll understand it when you see it.

JackBauer · Oct 23, 2023

ever get this fixed? ive tried cleaning the gas inlet and replaced the purge valve still have the issue.

mookieit · Oct 24, 2023

JackBauer said:
ever get this fixed? ive tried cleaning the gas inlet and replaced the purge valve still have the issue.

Yes.

A smoke machine showed the leak was coming from the vapor canister.

Replaced it and the issue was resolved.

cobrachris · Oct 27, 2023

mookieit said:
Been having p0456 small evap leak code for a few years now.

I erase the code every time it happens.

Noticed that the code typically happens when the gas tank reaches about half empty after gas fill up.

Changed recently the purge valve and treated the gas cap with WD40 silicone.

Has anyone experienced the same? How did they resolve it?

Or please share what else could I check?

cobrachris · Oct 27, 2023

I had the same code,wouldn’t pass smog I don’t know how you’re passing smog since the code is still in the computer.I had to replace the gas tank because it had a crack where the vapor hose attaches.$1,900 for tank and install,still ticked about this.

cobrachris · Oct 27, 2023

cobrachris said:
I had the same code,wouldn’t pass smog I don’t know how you’re passing smog since the code is still in the computer.I had to replace the gas tank because it had a crack where the vapor hose attaches.$1,900 for tank and install,still ticked about this.