Have not dealt with this yet, but PA requires 'visual and gas cap' tests begining with 1975 which is what I have. From what I read... in PA a 'gas cap test' is just that. They put your cap on something that checks the seal. However, I also read that CA 'smog' machine is fitted between the car and the cap to test the system. Would love to here more details on either test from an inspection mechanic...
