Symptoms of a failing Gas Cap

Check engine warning light comes on

Hey look, it’s your favorite indicator light. Yeah, I get it. Your car is driving fine, so why do you need to listen to that tiny little light, right? Well, because you might be able to stop a little problem, like a malfunctioning gas cap, before it turns into a bigger problem. If your gas cap isn’t creating a complete seal, it will allow fuel vapors to exit the system. This will be detected by the evaporative emission control system, which will notice that something is funky. And just like that, your check engine warning light will come on.

Gas cap warning light

Oh great, another warning light! Many modern cars have a gas cap warning light, to let you know when the gas cap isn’t on. Usually this is because you simply forgot to put the cap back on. But sometimes it’s because the cap is on, but not forming a good seal. This can be due to the threading wearing down, or just damage on the gas cap. But if the light is on, even though you’ve put the gas cap back on, you probably have a faulty cap.

Gas cap doesn’t screw on

You also might notice that the gas cap isn’t screwing on correctly. Maybe it never clicks into place, or maybe you can just feel the cap being loose, or not holding. Either way, that’s not good, and that will allow vapors to escape the fuel tank, and debris to enter it.

Car cabin smells of raw gasoline

There's a place and time for everything. And the gas station is the place and time for the smell of gas. Not when you're out driving your car. If you notice that you smell raw fuel while you’re in your car, it could be due to an issue with the gas cap.