Troubling p0456

9913 Views 10 Replies 6 Participants Last post by  guy65
Have a 2008 Ram 1500 with 5.7 L Hemi

Truck keeps throwing p0456...

There is a new mopar gas cap...
The truck was smoke tested...nothing
Was told that purge valve was ruled out.
I've also changed the EGR Valve twice now and the PCM last year because it was malfunctioning, i.e. burnt 4WD and likely the EGR too.

Something of interest, when the tank is filled, it almost always spits gas - even when filling on slowest setting.

I need to pass emissions and need to hopefully resolve this without lots of expensive exploration. Anyone have any thoughts or does this sound familiar?

Thank you.
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For what its worth, I had the persistent P0456 code and found out that if you keep you gas tank at least 80 percent full the code will never show up. Its a hassle but you could pass inspection that way. Finally had it fixed, they replaced a canister and another part and the problem is gone. Make sure you clear the code before you do the 80 percent fill thing.
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