Check engine light on a 2000 Hyundai accent?

My check engine light's been on for abut 2 weeks now, it came on during a long drive from Maryland to Savannah, Ga. I'm gonna get it looked at when I get a check i'm waiting for, but i'm wondering what could be the problem. The car seems to run fine, i had it inspected before i came to to Georgia and had everything fixed that need to be. The only two things that need to be done is the power steering fluid needs changed and so does the break fluid, but he said it's not a necessity at the moment. But would that cause the check engine light to come on? It also seemed to be idling pretty roughly but i put some fuel injector cleaner into it and it seemed to have worked. Another thing is on the ride down i hit a lot of pot holes, so could that of loosened something to cause the light to come on? I'd really love some opinions before i take it in to get checked.