I took my S60 to the shop yesterday and had a smoke test done. He couldn't find any leak.
The system failed to pressurize the tank. The mechanic thought it might be a check valve is staying open.
A new "Volvo" gas cap has already been replaced. Does anyone know where is the Evap Purge Valve located????

Thanks

 

Hello, I'm a newbie here. I stumbled upon this thread and found it very informative for me. Thanks for sharing.

 

I found the purge valve. It is located on the drivers side of the radiator. I found one online for $45. Should be a 5 minute fix when I receive it.