KMP

hi has anyone had any problems with the airbag on audi A3 2004 2.0 tdi 3dr, my light is on constantly and i have checked under the seat put its still on, any ideas what else it could be ?

I own Audi A3 2004 2.0 Tdi and the glow plug light keeps flashing and then switches off after couple of minutes, does anyone know if this is a easy fix, and how much it will cost ?