[quote=""bonerp""]Are these things supposed to record faults??!![/quote]
They are, but Sir is assuming that the recording system (a) works and (b) has a sensor in the right part of the system to notice a fault condition and (c) the Dealer's 'Technicians' are looking at the right data.

How many of us have been told that no fault has been recorded so there's nothing wrong
From my experiences with BMW, that does rather tend to be a bit optimistic - call me cynical, but around here diagnosis is not usually right on the first (and frequently not on the fifth either) attempt. Unfortunately this seems to be a common problem with many Dealers for almost all manufacturers now. The cars are simply too complex for the Service Teams to work on.
In the computer world we have a phrase CiCo (pronounced Phsyco) for Cr@p in, Cr@p out!! The programming and fault recording systems are only as good as the Programmer and Systems Designer, and the bean counters sitting on their shoulders of course.
