Try and give us a little more information about the light and the way your car is driving and your car in general.
Is it the Malfunction Indicator Light? I had that one turn on awhile back, I had the code cleared and in 5 mins it was back on. Turns out the aftermarket down pipe was broken and the sensors in the exhaust weren't reading right, and the engine was running a bit rich. Got the down pipe fixed and everything's been fine since then
take off the negative battery terminal off the battery for 5-10 min, make sure you got the radio number) then back on, if the light still stays on it could be a thousand reasons why its on, you have to get it scanned to see what the problem is. Pepboys or advanced auto will do it for free. Then you have to look up the code in the book.