Here is a related thread I posted in back in 2010 related to this issue: https://www.northamericanmotoring.co...mpartment.html. My cables/circuit box were replaced before my 4/50K warranty ran out.

 

I'm bringing this back to life share my experience so far with a similar issue.

My 2004 R53 developed a serious leak, filling the battery well. Boot carpet/foam was *saturated* and I had water sloshing around there in a big way.

I punctured a couple of the seals in the well, cleaned stuff up as best I could and was greeted with the airbag light as others have mentioned here.
The diagnostic error was 0b Ignition Circuit ZK10 / Safety Battery Switch 1.
I can clear the airbag light (got a small handheld device and also went to a garage) but it will still come back when the car restarts. Reading this thread and similar ones this happens because of a "self test".

I also had an error with the PDC Rear Centre Right Converter. (Unrelated I think)

First thing I did to try and fix this was get my hands on another orange fuse box, located next to the battery, where the positive cables meet. Got it from another car being broken up.. Replacing this fuse box and cleaning the contacts as best I can didn't fix the issue. There is still a bit of corrosion on & around the contacts. Perhaps that's enough to cause a problem?

The car otherwise runs and starts absolutely fine. My next attempt was replacing the entire positive cable (the one with the BST blow-off thingy is). This was again a second-hand part. Entirely possible that it was no good as well, but I have exactly the same issue with the airbag light.

The latest theory now (from my local garage where they replaced the cable) is that quite a specific BMW/Mini computer is required to reset the thing to basically say "there hasn't been an accident, everything is alright".

I'm going to a mini specialist here in London who thinks he can resolve this, so I'll post the outcome here.

Does anyone have any further ideas? Has anyone had a similar experience despite replacing the fuse box and replacing the positive terminal with the blow-off switch?

 

Did you ever figure out what the problem was? I have I've replaced the box and fuse and cleaned all the wires but don't want to get into the cost of replacing everything else without knowing if there's a simpler fix.