Blacksail, what did you end up doing??
I'm running into this problem now, unfortunately my warranty went out 3 months ago. Funny how this shit happens like that. It happened when I was at very low speeds 5-10mph and was actually coming to a stop.
I've checked fuses, reset using BT, and after a little driving 5F3A pops using my BT. No grinding noises, I feel more of a skip/hesitation and then the code pops/dash lights up (AWD,DSC,ABS) and the hesitation/skip goes away.
I'm hoping it is just the motor which looks like an easy replacement from this DIY. http://www.e90post.com/forums/showthread.php?t=633200
Sorry to bring up an old thread, but I'm wondering if we'll see more XI's with this issue. I hate to take it in for diag and them tell me what I already know.