airbag warning light on 2006 Mercury Grand Marquis

airbag warning light comes on when enging starts. Stays on.

2 answers
The light should come on when engine is started but go out when engine is started. The computer sees a problem with the SRS/air bags system, a scan tool is required to retrieve codes stored and locate the problem.
This can be dangerous and should be checked by a professional-if the air bag suddenly deployed while you were driving you would likely get into an accident.