I've had Pre-sense unavailable errors before, which I think can be caused by a dirty windscreen on the part in front of the rear view mirror where there is a camera. I've been able to cure that simply by using the screenwash button before.
I just got a new failure chime today though: SOS Call Function partially unavailable. The alert icon then vanished several seconds later.
The big problem is that these alerts are so very distracting, because they can relate to the Pre-sense system - and if that were to trigger due to a false-positive from a sensor it could be catastrophic. So you have to read the alert carefully while driving - not great.