MY04

Did a search, didn't find any concrete advice.

Haven't modded ANYTHING on my car in over 4 months -

get out of the movie theatre today and start driving home and realize my AIRBAG light is on - don't know why.

Any ideas?? I have an aftermarket audio system - all installed by me 6 months ago.

One minor point - (probably un related) have noticed my battery needs replacing soon due to teh cold weather - (starting to get a little weak when i crank her in the morning)

HELP! Can't figure it out!