Audi A4 Avant 1999 Wheel Motion Sensors

Hello All

I'm faced with the doubtful pleasure of renewing a front outer CV joint
boot. I've read up fairly extensively on the subject and think I know of
most of the pitfalls, the notorious pinch bolt et al. The one thing
remaining unresolved in my mind is the removal of the motion detector sensor
for the ABS system. All the accounts I have read glibly mention removing the
sense head without any reference as to the best way to do so. I have held
the outer part of the head as tightly by hand as I can manage and it will
not move at all. There are a couple of extremely inviting flats on the head
of the sensor which just invite the application of spanner pressure, this
I'm reluctant to do as the head appears to be plastic and the last thing I
want to do is to damage it (the cable disappears to places unknown and there
are no visible junctions, hence it could be quite tricky, as well as
expensive to renew).

Has anyone experienced similar problems? Did they find a a solution? Has
anyone broken the head of the sensor attempting to remove it? If so, was it
easy/ expensive to renew? Where is the connector for the feed wire for this
item?

Thanks kindly for all assistance.