When I was getting intermittent TFS errors on the 4.6is it was the trans position switch on the side of the trans.

I pulled the switch and checked continuity at various positions and it was out of spec.

Known issue on the ZFs and there are DIYs online to open up the switch to clean the contact points to get it working again. Followed the instructions and it thankfully fixed the problem.

__________________
04 X5 3.0i auto
03 X5 4.6is