Wanda,

Basically the ScanGauge is a little box that folks can buy for their cars to display information from the on board computer that is built into all cars in recent years. It can show things like how much fuel your car is burning and so forth. It can also provide error codes to you when your check engine light comes on to give you an idea of what might be wrong.

See the following link for info on the ScanGauge:
http://www.scangauge.com/