Ford Repair: ever hear of this? check engine question, plymouth acclaim, great shape

Question
92 plymouth acclaim automatic. great shape. took it for an oil change and inspection check up. i passed. while pulling out of the place the "check engine" light went on! thought this was strange as it is never on. figured it would go off. but has been on ever since, a week now. what could this be? have had car a few years and check engine light is never on. have oil changed and inspection and leave place with check engine light on!! it is a valvoline place and they don't do repairs, so i have not brought it back to ask them about it. thanks, rick

Answer
There are literally thousands of codes that can set off a check engine light.  On a 15 year-old vehicle it could be anything.  I'd check around, some shops and parts stores will  plug in their scan tool for free, and that might tell you exactly what's wrong.  
Jason