why is my check air bag warning light on?

Because there is a fault in the air bag system. Get it looked at by a shoop to determine why.

There is not always a problem with your airbag system if the light comes on. The manufacturer requires that your SRS be checked every so many yrs. Your light coming on can be a result of the system just do for a checkup. However, you should take your car to a Lincoln, Ford, Mercury dealer to determine the answer. There is a good possibility that your SRS does indeed have a fault.

The Air Bag lamp will not illuminate for maintainance. If it's on, there is a fault in the system that only a shop can scan and find.