Lunchbox

Service engine light was on when I bought the car. Had it checked out and it says P13 - Someone said that it was a Air Injection Canister problem and my mechanic neighbor said that it could be something as simple as a faulty gas cap. Anybody have a similar problem? I would sure hate to buy the $675 worth of parts to find out it was a gas cap, a replacement cap around here is $20 but it has a lock on it...ugh... I personally prefer the stock one that has a tether on it to keep me from driving away with still on my roof...

__________________
1998 Volvo v70 Wagon, (needs some TLC)
2003 Chevrolet Blazer 4x4
2006 Suzuki GSX600F motorcycle
1998 Oldsmobile Silhouette Minivan
all i need is the convertible and I'm done...