From the RNS 510 Users manual.
Convenience radio coding
If the unit is removed and reinstalled or the ve-
hicle battery disconnected, you will no longer have to enter the anti-theft coding manually as the code number remains stored in the vehicle when it is entered for the first time.
If the code numbers do not match, however, e.g. because the unit has been installed in another vehicle, the electronic lock must be released manually => page 8, "Entering the PIN ".
Code number
The code number can only be requested "on- line" via the Volkswagen system thus making more effective anti-theft protection possible. Please contact your Volkswagen dealer if you re- quire assistance.