Greetings all, I have a question I can't find an answer to via forum searches. My apologies if I missed something obvious and am asking again. Anyway, I've been chasing the source of these trouble codes for some time. The last time I took it to the dealer and paid the $90 to find out they had to replace a 3 inch section of vac hose. It is on again, saying small and large evap leaks. First thing I did was to change the gas cap; it seemed to work for awhile, but is back. I've scoured the system to find a sign of a leak but no dice. I have heard that a non-oem gas cap may not work properly. IIRC, I got mine from Napa. What is the chance that the napa cap is the problem and I would have to go get one form the dealership? Hate to spend the $ for a new cap, but also am tired of having that darn light on the dash. Thanks in advance.

 

Can't help you much in respect to the cap. I have read of people having problems with aftermarket caps but then they must have had a problem with the original OEM cap in the first place. My 96GC still has the original cap.

Here's a video that talks about your codes. It shows the most likely leak points and how a shop troubleshoots with a smoke generator. If it comes to it again then you'll know what they look at. The P0445 in the opening scene is a boobo. http://www.youtube.com/watch?v=CSn0ljUS6kI

 

You may want to take it in for a smoke test which will pinpoint the problem pretty quickly.
Places to look are the vacuum line behind the air filter and all of the hoses under the driver's seat. In my case, I had a bad hose at the canister under the driver's seat but I also had to replace the fuel inlet assembly to finally get the codes cleared.