Volvo Repair: OBD code PO442, advanced auto parts, emission control system

Question
I have a 1998 glt v70 Volvo wagon.  I love this car.  I purshased it used approx 14 months ago and it's been great.  Yesterday, my "check engine" light came on and I drove my car to Advanced Auto parts to find out the code.  The code that appeared read: "P0442 EVAP emission Control System Leak (small)".  The gentleman behind the counter said I needed to research the code and see what part I needed.  I'm just not sure where exactly the leak is coming from and I can't seem to find the right info.  I'll do everything in my power to avoid going to the Volvo dealer.  I have a great muffler guy that may be willing to look at it, but I don't want to waste his time.  Any suggestions of what to do next?  Thanks!

Answer
 Kelly, only one way to handle this. First, make sure the gas cap is tight and the seal not leaking. Then you will need to perform an evap system leak test. You need a "smoke machine" with a leakage/pressure guage. You inject smoke into the system and then watch to see if the pressure drops over a certain period of time. That's what the OBD II syatem does. if it doesn't hold, it sets that code. You watch for the smoke escaping to pinpoint the leak. That's the only sure way to do it. Otherwise you are just guessing. You need a pro=guy with a brain, and the proper equipment to do this. HTH

Mark