Evaporative emission control malfuction

I am getting a P-0440 code on a 1999 Lumina LTZ 6 cyl 3.8L. The book says "evaporative emissions control system malfuction". Anyone have an idea of what to look for? Is there any likely-hood of a performance issue?

Thanks for your help.

Jim

Check the gas cap and the hoses going to the canister in the left rear fender behind the wheel...

I recently posted a P0446 which is a small leak in the evaporation system. I first replaced the vacuum purge solenoid (on top of engine), then the gas cap and finally the vapor canister valve (behind left rear tire). The code disappeared after the vapor canister valve was replaced.

Thanks for the post. Right now my daughter hasn't had any more code issues. We checked the gas cap and canister but not the valve. If the code reapears I will check that as well.