If it is something serious your car will revert itself into a limp mode, and your car's performance would be cut in half. Start your car up, and check where the RPM is at an idle, it should remain at a constant number. If you have a rough idle then the RPM will be moving up and down noticeably, and is indicative of something not running right. Otherwise it is most likely just a sensor. Even the smallest bit of a different sensor reading that only happened once for a millisecond can turn your engine light on so it could be nothing.