Suggestion: Pull the steering wheel airbag and check its ground wires and all connectors. I says this as when I retrofitted my Si with a M-Sport wheel I ended up setting a similar fault - cause I forgot to tighten the ground wire nut.
I cleared it with a PA soft knockoff - something you may also want to look into. you can probably find it cheaper but here's a link -
http://www.resettools.com/bmw_scanner_1.4.0
Once the fault sets it probably wont clear on its own. It could have just been intermittent.
Heres a link for steering wheel removal - its not too hard.
http://www.zpost.com/forums/showthre...steering+wheel
Good Luck