service engine soon - gas cap

The service engine soon light popped on my wife's 2001 Spyder and she noticed the temp gauge flucuating. I drove it and decided the thermostat was toast. Replace it and reset the SES light. All was well for a few days when the SES light came back to haunt us. The temp was rock steady this time. I was afraid it was two different problems. Anyway, as suggested by searching the forum, my wife went to Autozone and had them check the code. Apparently, it was the gas cap tripping the code. They of course tried to sell her one. Looks like the seal (o-ring) on the gas cap is prone to fail with age. My question (finally) is where can I get a good quality gas cap? I'm sure the OEM one from the dealer is expensive. Is there a lower cost alternative?

Everyone talks about Autozone but I dont think they are up here in Canada. Anyone know of a dealer up here that will put your vehicle on their system to check the codes?
 

gas CAP? the black part that goes on it? the SES does come on sometimes when you dont tighten it down very well and it is a problem every ONCE in a while. just tighten it down 3 to 4 clicks and you should be good. go to autozone and have them clear the code unless you have a OBDII which you can clear it yourself and your problem should be fixed i get it every often because i dont tighten it down to well sometimes when im in a rush.

I guess mine may be aftermarket then cause it is a locking cap and spins freely when locked so I dont think you can not have it tight or it wont be locked (spinning)

you just hear a click when its tight. 3 clicks means its tight enough it will keep spinning.

    If a  new cap doesn't fix it put the car on a hoist and check the filler neck for rust. My wifes lancer rusted right through the filler neck and there was a lot of mud/dirt caked around mine.

I cleaned the gas cap rubber o-ring and the threads in the filler tube. That seemed to work for a while and the SES light stayed off for a few days. I filled up yesterday and squeezed in more gas than usually. Don't know if overfilling it was the reason, but immediately after I pulled out of the gas station, the SES light popped on. Both my wife and I have been making sure it clicks at least three times since the first time this happened.

Just don't know if I should bite the bullet and spend extra cash to get a cap at the dealership or whether the cheapie gas caps at Autozone are ok. Since the gas cap clicks to keep it from being overtightened, I guess that means it's spring loaded, so maybe the spring is getting weak? Alternatively, I've consider pulling the o-ring off the old gas cap and seeing if the local hardware store has a new o-ring that is the same exact size.

try it
itdont work return it =D