Engine lite stays on '95 Saturn Why?

I have a '95 Saturn and after driving it around 5 mi. the engine lite comes on and stays on. I've changed oil, filter and air cleaner and had the engine flushed. I disconnected fan switch -- temp.switch and ran it and it still comes on. Also disconnected battery postive post and left it overnite and the lite still comes on. What else could be wrong? Thanks so much and have a nice day.

Take it to the shop and have them scan the code and see what it is..

I'm not getting a code.

did u hit the reset button after the oil change???