I have to disconnect my battery in my 99 a4 because the airbag light is on. People say that i need to know my radio code What is that?

 

its a 4 digit code and should be in your service record or with the audio book but why do you need to disconnect the battery when you don't know whats wrong? you might be wasting your time and best get the fault codes first with VAG or other and they will be able to reset it without taking the battery off