There are possibly 2 lights. The first is for the main (drivers) airbag, the second is for the passenger airbag. Sometime the second airbag needs to be disabled (such as when you are carrying a baby in the passenger seat), and when it is disabled it can cause the related airbag light to flash. If you can find it (different places on various cars), check what position that switch is in.
If it is not this, you will need to get it onto a DiagBox system, to diagnose what the problem is. A generic reader probably won't help. You can check here for forum members who have such equipment and are willing to help;
James ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
Ex C5 2.0HDi VTR
Ex C5 2.0HDi VTR
C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!