2002 Chevy Cavalier Code P0440

I have a 2002 Chevy Cavalier with the check engine light on. I have found two broken wires on the small wireing loom by the fuel tank. I have installed a new fuel cap which I got from our state inspection station. I have disconneted the battery for about one hour to reset the computer, after about 90 miles the light comes back on. The computer code is P0440. Could my problem be in the evap purge solenoid or the canister is pluged. Any help would be a great help.