I have just bought a 2006 A4 with the RNS-E audio / nav system

Due to the usual problem of the battery being half underwater I need to remove it to clean out the scuttle drains.

I don't have the radio code but the owners manual suggests it MIGHT get synchronised to the car so as long as the unit goes back in the same vehicle it won't prompt for a code 

Does anyone with experience of this know if this is true ?

I have read the serial number with VCDS Lite so guess I can buy a code if I have to. They sell for less than a fiver on ebay, do these work ? Obviously a bit worried I might brick the unit.

Any help welcome, first time with an Audi so apologies if this is a basic question

Mine is a 2009 A6, so not the same but I have disconnected my battery and even replaced it without coding anything and all is ok.

Hello Paul,

Buy yourself a cheap ‘code saver ‘ device and cadge an old spare battery and charge that overnight. Connect the code saver to the spare battery and the other end into the cigarette lighter. 
You should then be able to disconnect your existing battery, and the car will remain powered by the slave battery, so no need for any code worries. 
Kind regards,

Gareth.