I currently have these two showing, I've checked tha gas cap and reset the computer a time or two, so I'm making an appointment with the dealer. Here's my question, could this be responsible for a 2-3 mpg loss that I've noticed?

Thanks,
Tim

 

it could be... I had one of those codes for a bad gas cap so what i'd recommend is swapping it, reset the computer (battery disconnect for 5 minutes) and re-run it.

there is a FAQ in the 2nd gen Ram forum that has some useful info that would apply here as well (this forum)

 

Don't know if this will help you or not, but the manual says this:

P0442 - A small leak has been detected in the evaporative system.
P0456 - A leak has been detected in the evaporative system.

 

yup, 442 is for a bad gas cap...