The AIRBAG warning light comes on when the airbag is not functioning correctly. ie it will not go off, even in an accident.
This happened to my vs berlina a while ago.
My mechanic used the tech diagnostic to reset it but it kept coming on still.
Ended up having to replace the "air bag clock spring" in the steering column.
It's only a $5 part but the airbag had to come out and ended up costing me $200 with labour!