P0452 Error Code

[dogsridewith]

Originally Posted by Spellino

Wait. So where can I locate those two valves?

What two valves? The only valve I've mentioned here is the rollover valve, which I didn't even know existed until this thread. Sounds like it is in the vicinity of where the filler pipe meets the fuel tank. If it was stuck closed, or near so, fuel would obviously back up in the filler pipe during fills.