2007 Chevy Impala Code PO455

DEREKM

MEMBER
2007 CHEVROLET IMPALA
6 CYL
2WD
AUTOMATIC
66,000 MILES

My 2007 impala (3.9) throws a po455 code.
It didn't throw this code until I added a can of Berryman's fuel injector cleaner. I reset the system with my scanner and after about 30 miles the light comes back on. I have tightened the filler cap several times and still comes on. I read that the cap has a pressure value in it and am thinking of changing it to a new one. I have looked for the evap canister to make sure no hose is loose. Can't find. Can you offer me some advice on where to locate and any knowledge you might have of a similar problem and possiable fixes.

I have watched the gas mileage and have not noticed a decrease in the MPG.

1 Reply

DOCHAGERTY

MECHANIC
9,601 POSTS

Major leak detection code p0455 is usually a cap, as you have suspected, and if there was a hose off, what would be the reason? Was there an excursion through the realm of the under-hood? I agree with your logic, I would encourage you to follow the path of repair you have chosen and test and/or replace the cap first. If that does not fix it, then it could be a crack piece of plastic or a leak in the evaporative system somewhere that is big enough to set a major leak fault, it shouldn't be hard to find. A smoke machine would be the tool of choice to pinpoint the leak. Not being a Chevy guy, I dont know where the canister is located, but if you smoke it, I guarantee you will see where the leak is, probably in one of the rear fender well areas, that is where the car engineers like to stash them.