Take it to the Dealer - might not be the cap at all; might be the pressure-sensor or possibly the filler-hose/Canister/Canister-hose is leaking.
It "assumes" that the cap isn't on tight-enough when it sets that code, as that's the most-common cause of the problem.
I would also make it clear to the Dealer you know about the proper cap-tension, and have checked and adjusted it multiple times - that way, they can give the car a closer look than "Oh yeah, just tighten the cap 'til it clicks. That'll be $50 please............"
It "assumes" that the cap isn't on tight-enough when it sets that code, as that's the most-common cause of the problem.
I would also make it clear to the Dealer you know about the proper cap-tension, and have checked and adjusted it multiple times - that way, they can give the car a closer look than "Oh yeah, just tighten the cap 'til it clicks. That'll be $50 please............"
