On 8/27/2013 7:38 AM, George wrote:
> (04 Cavalier) I'm getting P0455. New gas cap didn't help, & I didn't
> see anything flagrant on visual inspection.
>
> Reading about the EVAP codes, it seems that P0455 means a "large leak",
> while P0440 means the self-test can't reach its target tank vacuum ...
> which I'd think would also imply a 'large leak'.
>
> Is there some useful difference between these codes?
>
> Thanks
>
My understanding is that they're pretty much the same thing, just the
threshold for triggering the P0455 is greater than that for triggering
the P0440. IOW you can have a P0440 without a P0455 if you have a small
leak but not the other way 'round.

nate