Two different problems.
Hi
I had mine coming on and clear the code and it whent out to come back after a year cleared the code again and it came back after 6 months and came on again with even shorter notice to finally become permanent.
And i had this code from carsoft
Code 01 - Internal ECU Error is equal to carsoft code 01 Airbag Control unit driver side.
But its not the control unit, i hesitated and took mine out and sent it to germany for repair and it came back say no fault found.
The TIS says following
http://tis.spaghetticoder.org/s/view.pl?1/06/37/18
Even do TIS says to replace the airbag the problem is not the airbag itself because there is nothing in it that moves or wears out until its deployed of course its the wiring to it, the slipring which connect the airbag and steering wheel to the rest of the car.
its easy to replace, here is a guide for the E39.
http://forums.bimmerforums.com/forum/showthread.php?t=1815747
One thing you not should to is like the picture take the ribbon cable out no need, especallly when putting a new slipring on , and don't turn it! because if you turn it left or right and then center the wheel when putting it on alligned with your mark it will snap of when turning the wheel oposit way.
This is not for the e39 but a better guide.
http://forums.bimmerforums.com/forum/showthread.php?t=671950
What you can do as a first test it testing the circuit of the slipring by removing the airbag and disconnecting the harness below and and put a clip in one of the ends their the connector below to steering wheel or at the top going to airbag.
And then check for broken circuit with multimeter if you get a buzz then it should be ok if not replace the slipring.
First of all Disconnect the battery before doing anything without battery the airbag can't deply, when taken put it on truck or roof facing up if anything happens.
My recommendation is to not put your probes on the connector connected to the airbag moste multimeters contain a 9 volt battery.
If the airbag light turns itself on and off then its usually the occupany sensor for passanger thats why it comes and goes when placing stuff in chair or someone rides along.
But a scan of codes is needed to determine the fault.
Did you guys solve your problems?