I experienced the yellow icon, and steering wheel that refused to unlock after work on a cold night. The sound of the steering column unlocking/locking when inserting and removing the keyfob was not happening.
2007 335i with comfort access, 54k miles.
1. Replaced key fob battery ($10 at Fred Meyer)
2. New vehicle battery (Was original battery. Received battery icon during numerous attempts to unlock steering wheel.)
First repair shop scanned the car and said that all computer systems were talking, but that "Circuit 15" was not responding. They wanted to look for a fuse/power supply issue.
I found in a bulletin a note about "KL 15" which is an ignition switch position. When the mechanism in the column fails, the ignition switch does not advance to KL 15. I explained this to the shop and they were not comfortable going further into the problem.
Showed different repair shop this DIY. They agreed this was likely the cause of the perma-locked steering wheel.
I was quoted $250 for replacement unlocking module and $500 labor. I received a phone call a week after ordering the replacement module. I was told they were mistaken and that BMW will not sell the replacement module individually. The module they had in their hands was for a 5 or 7 series and had a metal case. You have to order the steering column. ~$1200 installed
I opted for attempt to repair the existing module. The mechanism had bound up and the plastic casing was open when they removed it from the steering column.
After cleaning and lubrication, they epoxy sealed it shut. Quoted $400-$500 for labor to do this DIY between different shops.
Sounds solid, works like new and going on 5 weeks now.
Thanks for this thread, it saved major headaches.