what causes the engine light to come on?
about car on 2001 Chrysler LHS
It means that there is a fault code in your computer controlled emission system. There are hundreds of codes and you need to have someone use a scan tool to retrieve it. It is better to have a real tech do it than a 'free' 'diagnosis' from a parts store, because most of the parts guys are not really trained in diagnosis. A code does not mean just a part is bad, there is often more to it than that.