Airbag codes 93B4 and 93A8 - Help appreciated

[Davz]

2006 facelift 2.5, 69k miles

I have the dreaded airbag light Codes 93B4 (drivers airbag, Stage 2) and 93A8 (drivers airbag, Stage 1)

Background history - Car started to have starting issues a couple of weeks ago in that it would take a number of turns of the key to get the starter to turn over and then at other times it would turn over on first turn of the key as usual.
Knowing that the battery can cause all sorts of strange issues I had it tested but was fine. Then the airbag light was thrown last week. So I replaced the ignition starter switch, which has solved the starting issue but as the ignition switch can also cause all sorts of strange things I was hoping that when I cancelled the error using a C310+ it would be back to normal, but no luck.

The c310+ tells me the code is cancelled but the light doesn't go out on the dash and on rescanning the code errors are back, so obviously there is fault somewhere in the system.

FYI, the c310+ reports a comm error and cannot access the sbsl or sbsr.

Tomorrow I'm going to check the connectors under the seats and then the airbag connectors in the door cards as I did have the cards off a few years ago when fitting extra door speakers. I have thoughts it might be the clock spring (horn is working) and am going to take the wheel off and clean up the connections. Or is it a module that has gone bad?

Any help/ideas as to the cause and repair greatly appreciated.

[colb]

With no commas to the side airbag modules I would suspect the main central module, if the code won’t clear the internals of the central module may have a fault. If you go down the road of putting a used replacement in it will need coding to the car using NCS Expert. Module must be like for like part numbers or a compatable module that your car can accept retrospectively details listed in Realoem site. If a used module comes from a crashed car it won’t code and needs expert coding using the eeprom on the internal board so beware when buying on eBay

[Davz]

Cheers Colb, that is great info and very much appreciated.

Is the module the one at the rear of the passenger seat that can short out due to water damage, which seems to be a common problem from what I have read?

Would this be the correct unit:-
72126967481
Air bag Module for passenger side

Once again many thanks for your help

[Davz]

Sorry Colb, another question, if I have a go at coding do I need a K-line or Dcan cable, my z4 is a late build 2006, but the ecu was made June 2006