When your car's "Check Engine" light comes on, it's usually accompanied by a sinking feeling in the pit of your stomach. The light could mean a costly problem, like a bad catalytic converter, or it could be something minor, like a loose gas cap. But in many cases, it means at minimum that you'll be visiting the car dealer to locate the malfunction and get the light turned off.
The Check Engine light â€" more formally known as the Malfunction Indicator Lamp (MIL) â€" is a signal from the car's engine computer that something is wrong. The car dealer's service department can diagnose the problem for about $75. But there's a way to preview what the problem might be.