Ok, the message "check gas cap" has been coming on my mom'* SSEi for over a month now. We took it to the dealer and they lookd at it. They charged us $80 just to look at it and say the gas cap was 'bad.' they replaced it and put on some new seal and say the car is good to go... drive it for a day and the ligth is back ok. The car has been to the dealer 4 times for this already and they can't figure out what'* wrong, thus the reason why I ask here. any other ideas on what could be wrong with her car? The gas cap has been replaced 3 different times with 3 different brands. (one GM, one from autozone, and one from advance auto.) thanks!

looks like its time to go to NAPA

well, I don' tthink that'* going to help. The gas cap can't be the problem. When they scan the code it'* something along the lines of "fuel system pressurization loss" or something like that. Basically the fuel tank is leaking pressure and it'* tripping the SES light.

Aren't you supposed to turn the cap a certain amount of times to get a good seal?

yep. 3 times. You can turn it 20 times if you want and it still has the same problem.

Actually it is a possible vacum lreak in the EVAP system. Either a purge valve or vent valve malfunction or any of the interconnecting lines between the fuel tank, charcoal canister & intake manifold in the EVAP system. Just throwing out ideas.

Fuel Tank Pressure Sensor?

Yes, another potential problem.

Cant remember the specific code 4014 i think....

An OmniScan tool really gave a HUGE amount of data for the
diagnostic of EVAP or "gas cap" it being the LAST on the list...
and the list is long Just SOME from memory...

Fuel cell pressure sensor (a likely culprit)
Fuel pressure regulator
Fuel pump relay
evap return vent
egr return
egr selonoid
egr vac
and several more little vacc hoses.
Fuel cell filler neck / neck vent
cas cap

I'm told the filler neck DOES crack and not hold pressure
and the scan tool monitored the "pressure sensor" and the
values were all over the place -2200 - 5600 -3600 etc.
so I'm thinking either the filler neck or the sensor on my '00
annoyin' as all get out!

Been there; done all of that. Let'* look at what happened to me.

I had a similar problem with my new 2001 Bonne after every fill up. The "check gas cap" light would go out after 10-20 miles or so, and return again after the next fill up. Mechanics tore their hair out, checking codes, testing cap, replacing cap, etc. Finally, one dude suggested that at fill-up I DO NOT OVERFILL BY ONE DROP once the auto fuel fill nozzel "cuts off". I thought the guy was crazy. Well, now I pull the nozzle out and cap 'er back up WITHOUT TRYING TO GET MORE FUEL INTO HER. I've never looked back.

Good luck.