In the fire service we have to know everything about every single cars air bag system because if we make a wrong cut with are tools we are dead it is as simple as that anyways back to the point in your car the is a back up battery and when we cut the battery to turn off the system so the air bags dont go off that is the same thing that is happening here it sounds like you. if i am wrong tell me but when you take your positive cable or your negative cable off your battery it then stores all that energy so that when in an accident if one of those cables to your battery is cut there is still power to set off the air bag just like a back up system. so if you leave the battery disconected for a long time that power is lost and the system has no power and then sends out the airbag warning light say that is was deployed or the back up power is no longer there

like i said if i am wrong tell me i want ot know it could save my live someday

 

Cheers guys for all the replies. I haven't been at my comp in a while and i apologise for the delay in replying. I'll check everything ye said and get back to ye if i figure out any solution. I might order a VAG cable and check for codes too.

Thanks again.