2010 4.6 P0456 Small evap leak

[chewpatrick]

I have a 2010 4.6 with 172000 miles. Runs great. only issue is CEL for P0456. Steps to fix. First I replaced the gascap with an aftermarket cap. Code went
away on its own but came back again after a few 100 miles. So I bought a hyundai cap and cleared the code. CEL came back quickly.
Replaced the purge valve and the vent control valve. Reset the cel but it came back on pretty quickly.

Car runs great. Occasionally I will get a faint smell of gas. I will have to say the hyundai cap is weird. One click only. But I assume the new cap is good.

For now I am ignoring the CEL but would like to fix. New canisters are expensive. I was considering a used one.

Any suggestions on what to try next?

Thanks in advance.

 

[atlanticmilklord]

I have a 2010 4.6 with 172000 miles. Runs great. only issue is CEL for P0456. Steps to fix. First I replaced the gascap with an aftermarket cap. Code went
away on its own but came back again after a few 100 miles. So I bought a hyundai cap and cleared the code. CEL came back quickly.
Replaced the purge valve and the vent control valve. Reset the cel but it came back on pretty quickly.

Car runs great. Occasionally I will get a faint smell of gas. I will have to say the hyundai cap is weird. One click only. But I assume the new cap is good.

For now I am ignoring the CEL but would like to fix. New canisters are expensive. I was considering a used one.

Any suggestions on what to try next?

Thanks in advance.

I Have the same exact issue. replaced purge valve, canister vent valve, gas cap, and the fuel pump( for other issue). I havent been able to pass emissions since january 2023, so i havent had a new tag since then. Someone please save us.

 

[Gunkk]

Any air leak in the a) gas tank (e.g. pump bung seal or secondary level sensor bung seal), b) vent canister and it's in and out hoses, or c) fuel filler cap, pipe and the vent connection hose, will cause this. The smell of gas fumes confirms a leak is present (and not only a component failure). So firing the parts cannon at it is unlikely to make it better, and might make it worse if poor quality aftermarket parts are used.

16 year old rubber hoses between the tank & vent, and vent & fuel-filler bung can and do rot out.

Best way to pinpoint the location is with a smoke tester, flashlight and mechanic's mirror. Any competent mechanic can do this, or if you have these tools and can get the car up on jack stands and rent a smoke tester, so can you.

Even without getting the car up in the air, you can also remove the tank pump cover under the back seat and inspect the pump bung for rust-rot and its hose for leaks. I believe the vent canister inspection cover is in the trunk (not sure, I don't have my 2012 anymore).

Unfortunately to get to the vent hoses at the tank connections you must drop the tank.






Vent can access:

 

[chewpatrick]

Gunkk thanks for the through answer. I do my own work within reason but I think i am tapped out on this. Now I need to find a competent fairly priced mechanic in NJ.