I searched for this but didn’t find anything. I have a 2021 F-150 with a 5.0, only 9K miles. Getting a 455 code, large EVAP leak. Definitely not something you’d expect on this new a truck. I’m wondering if this might be a common problem on this truck? With this new a truck you can rule out what would normally cause this code. I’m thinking solenoid?

I know it’s under warranty and I can take it to the deabut they are two weeks just to check it out. If it’s something simple I would rather just fix it myself and be done with it.

 

Could be something as simple as a fuel cap or flapper not closing properly. If you have the cap-less filler, try funnel humping it to see if there's crud in the assembly that's keeping it from sealing properly. If it has a "normal" cap, make sure it's sealing properly.

In any event, it's an emissions-only concern that won't affect drivability. It's also a warranty item and the dealer will eventually get around to it once you can get it in if the easy stuff doesn't resolve it.

 

It’s cap less, I’ll give that a try. Thank you. I’m not concerned about the drivability, it’s fine. My wife on the other hand…well…check engine light is on, time to panic. 😂😂
I’m not a fan of dealerships for repairs or even oil changes for that matter. I was hoping this was a common problem like a loose connection or loose hose that several people had dealt with and I could easily fix. I’ll let you know if the funnel humoring helps.