The light on the dash came on and I pulled the code and P0441 P0455 on 2008 Scion tC

This is a 2008 sicon tc, I reset the light and it came back. Some one said it is the gas cap or the prurge valve...
Not sure hot to check to see the the valva is working? What elso might be?

Asked by for the 2008 Scion tC
We have diagnostic equipment that can activiate the valves to see if they work. First check the vacuum lines form the tank to the engine. Make sure nothing is disconnected. Call Dublin Auto if you still need help and ask for Jon. (925)828-0243
I check the lines from the tank to the engine and every thing is fine. The Valve by the air box we checked and its working. I bought a new gas cap just to be on the save side.. How do I check the valve by the canister to see if it is working? This on a 2008 Scion TC 88,000 miles..
Our computer activates it. Do some research on the boards. You might find some common thread.
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