This may seem like an obvious one, but if you neglect to get your car checked when any of the automotive warning lights come on you could be neglecting a serious problem. The check engine light, and other warning lights, can come on for a number of reasons. The good news is that all of them aren't necessarily going to be a major issue. But you won't know until you get it checked out.
In addition to the typical check engine light, many cars have several other lights that come on to indicate a problem. They can warn about problems with the alternator, battery, engine temperature or other areas surrounding the engine that are monitored. To protect your engine, either run a diagnostics check when the light comes on and then fix the problem yourself, or take it to a mechanic so they can run the test and perform the work. If you wait too long after the light comes on you could allow a small problem to develop into a big one.