just for future reference, and not to be a dick, but anytime your cel is on, your car is having a problem that should be addressed asap or as soon as funds allow, getting the car scanned is free at most auto parts stores. a free scan could save your engine from blowing up if you let it go as ahh it still runs ok.
when the cel light is on you are not getting all the performance or mileage out of your cars full potential. once you get this figured out im sure your car will thank you by running like you never felt it run before.