Say you’re driving down the highway and suddenly the check engine light comes on. Everything seems OK; it’s not sputtering and the gauges look good. So what’s that little light all about? Keeping an ear to the motor’s hum and an eye on the vital gauges you continue on to your destination. Since nothing seems wrong we’ll put up with that light, hoping that it goes away. But if it doesn’t go away we’ll eventually take our car to the shop to find out what that little light is trying to say. The mechanic will plug in a little gizmo