Just put my first tank of gas in my "new" 2001 SSEi (30,000 mi.). First around-town (under 20 degree F avg. temp) mpg was 21.5.

Drove about 10 miles to work. When I restarted car at lunchtime, no probs. Drove about 6 miles and noticed a "check gas cap" message. Dang, forgot to tighten the cap. Got out, checked it, it was on tight. Pushed in on it to get some more torque and she did turn in a little more. Since that time, today, I've had about 10 starts and each time I get this message, but just at ignition. I can clear the message by pressing the reset button and the message stays off, but each time I start her I get that message. The car idles smooth as silk.

When I got her about 2 weeks ago the dealer loaded up the tank for me. No message til now.

What gives? Could this be a freakin' concidence that on MY FIRST REFILL the cap goes South. I've placed plastic wrap under the cap just in case the cap IS leaking. I get the same message.

What does the system do, measure tank vacuum or something and if it is low it trips the switch. Where is that switch anyway? In the tank? LOL :(

BTW, I still have about 3 months or 6k miles left on my dealer warranty.

Yup the poor seal gas cap thing. I think this is gm'* way of keeping in touch with its customers. You need a new cap by the way.
The sensor does work off of vacum and the warning is to ensure you dont get an air lock in your fuel system.

Thanks pontiacday,

Unfreakinbelievable

One other curiosity....I'm almost embarrassed to mention it.
I did break the golden rule and pumped a tank of 89 octane in her. She runs fine though. No knock either. Surely that little switch isn't ratting on me is it?

PROMISE YOU WON'T TELL ANYBODY ELSE ON THIS SITE WHAT I DID!

Its safe with me
89 is ok for now, you could add some octane boost but if your not going out on the open road for a trip just let it run down to 3/4 then fill with premium.

okeydokey

That'* a good one.

Gas cap problem on your first refill?,...sounds like more than just a coincidence,IMO,....and probably(since you said the cap was tight when you checked it) more than a simple gas cap seal leak.Take the car back to where you bought it and have them diagnose and fix the problem,....most likely other component/* are the cause.Don't worry too much about the 89 octane gas you put in.....the car will run fine,....I've put tanks of 89 in my '97 Grand Prix GTP (when I owned it)and tanks of 89 in my '00 SSEi,with no detectable change in the way the car runs or performs....

HAHAHAHA!!! funny stuff

Your a bad man Charlie Brown. If you don't push the car hard this may be ok once in a great while, but dont do it often. Supercharged cars like to run lean because the forced air is making a more air heavy fuel mixture. If you start taking away the octane to help it burn this your going to get a ton of knock and that will be bad for your gas mileage and your engine.

I wanted to repost this 2-day old inquiry to find out if I'm being fed a line of crap by GM.
I'm the guy who'* been getting "Check Gas Cap" message since my first refill on my "new" used 30,000 miler.

Today I called the dealer where I bought the car. They said, "sure, bring her in. You have 30 days left on your warranty so everything should be covered." They said, though, that I could take it to a local dealer for service cause that would be 30 miles shorter distance (1-way). NOW BEAR WITH ME PLEASE.....................

I called the local dealer service tech. He told me to make an appt. and they should cover repairs, IF THERE WERE SOMETHING WRONG . I said, "ok, suppose the gas cap was loose (which it was not). How do I know if I corrected the problem?" He said, "well, you can't right away". "You see, the system pressurizes and checks the tank for pressure leaks on a random basis, not with each start. He said it may take between 100 to 200 starts-and-runs before the system might recheck itself. I think, "Sure, right! Let'* see.... 4 starts per day...........that'* about 25-50 days worth of starts before I find out if I really do have a pressure leak at the cap????" Gee, the warranty'* over then!!!!!!!!! This gives me only one option. Off to the dang dealer I go.

Questions: 1. Does anyone really know if this crap is true? If it is I would like 5 minutes, alone, with the engineer who designed this system. Surely somone on this site knows exactly how the system operates. How about it guys/gals??
2. Can I reset this slimey little message by disconnecting the battery for awhile?
3. If I can, will the system immediately re-check itself or does the programming demand that it go through that silly random sampling thing.
4. I spoke with Autozone personnel (usually VERY helpful). They said they might be able to read a code, but they were not permitted to clear it. COME ONNNNNNNNNNNNN.