Why is my chevrolet cobalt check engine light on?

If You have a check engine light on at the dash of Your Chevy Cobalt the first thing You should do is try to get off the road. Driving with a check engine light on can cause more damage to Your motor so You should avoid doing it. When You have stopped You should use an OBD II scan tool to read the codes that are stored in Your ECU to see what caused the light to turn on. The most common problem is a large vacuum leak in the engine. This is usually caused by a loose gas cap. If You have a check engine light You will need to fix the problem before clearing the code otherwise the code will just come back on.