Car Trouble (O2 Sensor)

My check engine light came on coming home from school, I went to autozone and they said it was the 02 sensor in my exaust, and if i dont get it fixed ill eventually lose gas milage and ill lose performance. And of all times I was due for inspection, which I failed because of this issue. But a day later The light went off. So im thinkin do I still have to get it fixed or did it just fix itself or was it never really broken. I havent noticed a decrease in gas or performance at all. what do I do? thanks in advance and my bad if this is the wrong place to post this.

Oh yea and I drive a Hyundai Accent 2002 GL.

Well I’m not sure why you posted this on a video game forum, but here goes: Your o2 sensor reads the air to fuel ratio in your exhaust gas, it basically communicates with the “computer” of your car to tell you how the car is running. They all tend to go faulty after some time. It is an easy fix but you will have to get underneath your car to get to it. Yes it can ruin your gas mileage, and yes it will cause the check engine light to go off and fail your inspection. Just because the light went away doesn’t mean it’s no longer broken, the light will probably come back and if it does I highly recommend you get it replaced.

BTW: If your car is still under warranty (I know Hyundai has some crazy long warranties), I suggest you take it back to the dealer as it should be replaced for free.

I had my O2 senors trigger recently from a bad tank of gas. If you run for another 50-100 miles your cars computer will complete a cycle, if the light hasn’t come on by that point you are proably good for inspection.

not really, if it doesn’t show up again, that means the ecu is richening the mixture so the car stays running, it is like this on all OBD-II cars.
Just replace it… it’s an easy 15 minute job.

Yup! Just follow your exhaust pipe and there should be a bung in it with some wires coming out. Use a wrench and twist that sucker out of there. Again, I know Hyundai brags about their 100,000 mile warranties… so perhaps see if it’s covered first.

All cars in the US are covered by an 8 year/80,000 mile emissions warranty. The oxygen sensor falls under this warranty.

This information should also be in your manual. If you have <80k miles on it, see your dealer and you should be covered. Good luck!