We’ve all been there. We are driving down the road and all of a sudden the check engine light goes on. Something is wrong with our car but what? The vehicle seems to be running fine. What is wrong? Before you take your vehicle into the auto repair and service shop, all you need to understand is that the computer is telling you something needs to get checked out. When you take your car for service the mechanic will run a diagnostic test with a scan tool to determine what is ma