Thanks for the info in this thread. Had P0238, P0401, and P0069 faults and the car going into limp mode. Replaced part 13627792260 (while in the dealers parking lot!) and all is well. Easy job. Faults stay cleared and no limp mode. Only downside was paying dealer price for the part ($132) as I didn't have days to wait for delivery of a cheaper one. Car is a 2009 X5 35d with 113k miles.