Almost all vehicles on the road these days have a check engine light. When this light comes on, the car's owner knows that something is not right. But when the light comes on, most people automatically think it is a huge problem, such as something being wrong with the engine. Fortunately, this is not always the case. When the light comes on, you may be having problems with your car's battery as well. Here are a few reasons why your check engine light may come on for battery problems.