Problems with central locking system have been traced to the pump, the
impellor of which has disintegrated. Audi dealer approached and says that
new pump is £290 with an additional £90 for "recoding" the system.

The maintenance procedure in both the Audi company stuff and the Haynes
material does not mention any such recoding requirement but merely refers to
a straight exchange of components. We have so far tried 4 second-hand pumps,
none of which operated the system, the last one running when commanded by
the system to blow but failing to run when commanded to suck and with the
immobiliser failing to arm when commanded by the key press. With the
original defective pump the immobiliser does arm. There are no leaks
apparent on the system by oral "blow test", with the filler flap locking and
unlocking by means of mouth pressure, as do the rear doors. Neither of the
fronts will move either open or closed for some reason (I suspect they need
more pressure than I can generate but I'm reluctant to start connecting air
hoses in case of over-pressurisation damage). The system rapidly charges
with air to the point where I can blow no more and the same happens with
suction.

Has anyone successfully changed this pump without the dealer's "recoding"?

I suspect the reason for the failure to perform on the part of the 4
second-hand pumps is that they are all as u/s as the one we are changing.

Thanks for all helpful replies.

Barty wrote:

exist.

Still, I seem to remember that there is a synchronizing process with the key and
opening / closing doors that might be what they are talking about. You might try
a search on AudiWorld.com or other forums for more information.