The check engine light; a light that many people will sometimes drive around with it on without checking into it because of the assumption that the light is on by mistake.  Maybe a loose wire or something.  It could also mean that something is wrong with the engine.  Shocker, I know.  The problem is in that the light doesn’t do a good job narrowing down what could be the issue.  Is it minor and easily fixed, or is the engine is serious trouble and needs to be service immediately?  Here is some of the top reasons why that check engine light may have come on in your vehicle.