You've probably had your Check Engine Light go on. Then it goes off, and you figure, whatever the problem was, it's gone now, and I don't have to worry about it. The problem may have gone away, but it may not have.

Your vehicle likely has one of these warning lights on the instrument panel: an amber light that looks like an engine or reads "Check Engine" or "Service Vehicle Soon." If that light comes on and stays on, it usually means something needs to be fixed but is not urgently in need of service. (Now, if it's blinking, that's another story we'll deal with in a minute.)

Sometimes, when it comes on and stays steadily lit, the problem will go away, and the light will go out. Sometimes, it will remain on until you get the issue fixed. Either way, the engine's computer will store a code that can provide clues to what's not working—or wasn't—the way it's supposed to.

If you are dying to know what that code is, you can buy a little code reader or take your vehicle to an auto parts store, and they'll read it. The problem is that the code offers so many options that you probably will only know what those codes mean if you are a trained technician. 

So, if you want to be sure, take it to your vehicle repair facility and have them check it. Technicians are trained to decipher the codes and, using their experience and other diagnostic equipment, can get to the root of the problem and fix it. 

As we mentioned, if the Check Engine light comes on and blinks, it means a more severe engine malfunction that can damage expensive components. Having that checked by a professional as soon as possible is important.