The check engine light or service engine soon like comes on when the computer recognizes an emissions failure. This can affect fuel economy up to 30%. When the check engine light is flashing the computer is recognizing a misfire which and even cost you more. Whenever your check engine light comes on you should have your vehicle check by a trained technician that understands how these systems work. Don’t delay emission problems result in poor combustion of fuel and increase carbon buildup, which is harmful to your engine. Ignoring the check engine light means you won’t be aware of other problems that come about and might increase overall repair cost in the end.