For the past few months, I've had a weird intermittent check engine/VSC light problem. I've noticed that it comes after getting gas...and sometimes goes away after getting gas. I've jiggered the gas cap to be sure it's tight. Is it possible that this is something as simple as the seal in the cap gone bad?

 

Well, probably wouldn't hurt to buy a new gas cap just to eliminate that possibility. I'm sure they're cheap and can be had for a few bucks. Or it could the be seal in the gas throat.

You try starting your car without the cap and or the cap purposely left loose to negatively test it? I wouldn't drive it under these circumstances, but it might worth doing just to see what lights come on. Start it, let it idle and see what lights come on. This all assumes those lights are related and it is not a coincidence.

Or you could just go the dealership and have them read the car codes or if you have a reader yourself, not a cheap OBD scanner that can be had at Autozone, but like the Carista app, you could see what codes are being thrown.

 

Definitely could cause it. Leaving cap off will get you a CEL

 

A properly sealed gas cap is an integral part of the vapor recovery system. The gas cap is designed to give audible and tactile feedback when it is adequately torqued. Tighten it till you hear and/or feel the "click" - every time.

 

I will be very interested in reading about your results of a new gas cap. That click is a must. Not heard of a cap going bad, but I'm sure they do. Don't know who you use for maintenance, but I'd consider getting an opinion from a service provider. Good luck.