Check engine light 2005 Hyundai Elantra?

What Matt said yes you need to have your car scanned to find the code that triggered your engine light. Most chain auto parts stores like Autozone do this service for free.

@Felicity: No the engine light comes on due to the PCM setting a trouble code. Air pollution only has a minute affect on electronic management systems on cars. They can usually compensate for pollutants in the air.

Sometimes the check engine light comes on because of air pollution, it's normally not a problem if that's the only thing going on. If your oil light which looks like a teapot comes on that's really bad. It doesn't mean oh you just need an oil change, it means your engine doesn't have any oil and it self destructing every time you drive it, never wait until that comes on to get an oil change or you'll blow the engine!!!!

It means you need to have the compute scanned so it can tell you what's wrong and NO, check engine light won't come on if you need oil. Your oil light will come on to let you know you need oil.