Evap codes

I have been having issues with my f150 that nobody can figure out, and I’m hoping someone has had a similar issue and can help me out. My truck is a 2021 2.7 lariat with a 36 gallon fuel tank. Since I got it, I have had 3 codes I can not get rid of. It has been looked at by 3 different shops and nobody can figure it out. The codes are

p04f0: Evaporative Emission Control System (EVAP) high-pressure purge line

P0455: large leak in a vehicle's evaporative emission system

P0456: small leak in a vehicle's evaporative emissions system.

Between the 3 shops, they have replaced the purge valve, the canister, and filter, and one of the connections around the transmission. None of those things fixed any of the codes. I have had it back in to 2 different shops after, and they smoke tested it, and checked the purge valve, and everything look totally normal. I haven’t had the truck very long and have had the codes the whole time I have owned it. The truck drives totally fine, but it’s frustrating having a light on! Any help would be greatly appreciated!

 

I was going to suggest they smoke test it but saw you had that done.

I have battled these evap codes before and they are hard to fix. I have always wondered if that particular test could be turned off in Forscan.

There is zero effect to the way the truck runs even though it fails this emissions test.

One last thing might be the capless fueling. Maybe it is not sealing as well as is should. On cars with gas caps, replacing them would fix about half the evap issues.

The good news is the test is not commanded by the computer when the outside temp is below about 40, and it has to fail the test like 6-7 times to trigger a light, so you shouldn't see the code during winter.

That has been my experience anyway.