Troubling p0456

9942 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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Hi huntergreen,

Do you know the name of the valve?
Is it a difficult fix?

Thank you.
guy65 - do you suppose it can also cause the p0456 code?

I'm not a tech, just a vehicle owner looking to troubleshoot.
As for the smoke test...I guess I won't ask...

Would a repair to this require dropping the tank? Thanks.
I apologize but did not realize that I was getting responses to this. This issue has still not been resolved. I'd like to add some additional information to this.

My truck is also experiencing the following:

1. If I "top-off" my tank, I may experience the truck literally shutting off while driving. It happened this March while traveling and fortunately it was only when I was moving slowly. I've not topped-off since and this has not recurred.

2. Under the center console, while driving, I will here what sounds to me like a solenoid trying to engage unsuccessfully. I produces a rapid clicking sound for a 2-3 seconds then stops.

I have to believe that all these are related issues.

I'm at 201K miles and the body is starting to decay a bit. I'd like to keep my baby as long as I can because it is otherwise a great vehicle. I just cannot justify the expense of exploration that involves dropping the tank.
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