There are so many possibilities for what a lit check engine light may mean that it is impossible to determine what is wrong just by the presence of the light alone. Something as simple as a loose gas cap may be the cause. Or it could be the equally no need to panic broken oxygen sensor or engine misfire. With this being said, you should still bring your vehicle in for vehicle precision service to ensure that you will not end up with major problems later on. Especially during the winter months, you want to be sure that your vehicle will not just stop running due to issues with the check engine light.