While working on a 2000 SSEi with this code, and checking all the usual problems, I recalled what DaveSSEi found in this thread.

http://www.bonnevilleclub.com/forum/...er=asc&start=0

Checking the line from the evap solenoid to the canister (the smaller line with the white end), it was attached properly and the clip was holding as it should. I gave it a push, and heard the same click that Dave found. There has not been any recent work done in that area. I took the connection off, cleaned things up and put a dab of silicone grease on. The code has not returned. Anyone experiencing this code may want to check there first.

Edit - That is after being certain the gas cap is on properly, and the top of the filler tube is clean.