Sometimes the light sensors on the dashboard of your car will go on and go off sporadically, causing you to be concerned about what is going on under the hood. This flickering of the check-engine light could mean a number of things, and you should investigate all of them to be sure your car isn't having mechanical problems.
Cars are incredibly complex machines, especially these days, as everything is programmed through chips and circuits. Sometimes there are glitches in the electronics, which cause sensor lights inside the car to come on, or faulty sensor switches that say something is wrong when really nothing is wrong. If the light comes on once and then goes off, keep an eye out for it, as sometimes a power surge within the electrical system within the car will trigger that light momentarily. In this case, nothing is wrong.
Is this check-engine light coming on and then going off at certain times, such as when it is raining, when you haven't changed your oil for an extended period of time or when it is very hot outside? These are all clues as to why this light is coming on, which you should take into account before coming to a conclusion.
If the pattern continues to happen, bring the car to a mechanic for diagnosis. Report the clues you have gathered. If the mechanic's diagnosis doesn't sound reasonable or sounds outrageously expensive, take the car to another mechanic and get a second or even third opinion. You may want to bring the car in, ask a mechanic to find out if there is a problem with the engine, without mentioning the sensor light, and see what he tells you. This is the best way to figure out if the problem is mechanical or just a faulty sensor or dashboard light.
