A4 Avant Central Locking Pump

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.