Since the airbag light is now an mot fail I had better get mine fixed I've read the codes and get these

B3902 - wrong immobiliser identifier recieved - present


B0015 (02) drivers pre-tensioner circuit low voltage - present


B0084 (o5) Right EFS circuit high voltage (05) -

have another pre tensioner to fit but where is the other sensor?

Also what's the top code for?