JDBlueAudiS4

It details how you need the SKC to match Keys (not key fobs) to the imobilizer system. I do not believe you can change your SKC or unmeld lost keys. I believe you need a new SKC, the only way to get a new one is to get a new cluster. This of course is unless things have changed (which they have recently with the new GEKO system)<ul><li><a href="http://www.ross-tech.com/vag-com/faq_4.html#skc">http://www.ross-tech.com/vag-com/faq_4.html#skc</a</li></ul>

Miah_S4Avant

[Adaptation - 10]
Enter 21 in "Channel Number"
[Read]
The "Stored Value" is the number of keys currently matched.
Enter "new value" of 0
[Save]
This clears out the old key-matchings.
Enter a "new value" corresponding to the total number of keys to be matched, including any existing keys
[Save]

Which means to me that the old valet key becomes useless.

JDBlueAudiS4

you can only prevent the key from starting the car. The car can still unlock the car as well as unlock the steering column. I asked them and they said as of the B6 platform you could recode to prevent old keys from working by use of the SKC provided by GEKO. In the B5 and previous platforms old keys "might" still work even if recoding happend. So long and short, whoeever has the valet key could still easily enter the car and steal it since they can unlock the steering column. Sorry for the confusion, I still thought that you needed a new SKC to prevent the old keys from working.

koolaid

Yes!