I just bought a new key from an online shop for my car (VW Polo 2007). The key blade works fine, but I haven't been able to program the key fob. I have tried various ways to do it (e.g. here), but haven't succeeded. There seems to be no official documents about this. Can anyone please help me with this?
How many keys does the car already have paired to it? Did you replace the battery or is this a new key fob?
If it is a new or 3rd keyfob, you have to edit the amount of keys via VAG-COM/VCDS, in Central Convenience/Adaptation/Run Group 00 to reset defaults and save. Then go into group 01 and edit the amount of keys (1,2,3 etc.) and run through the pairing procedure. Save and Exit. Turn off the car and then lock/unlock it.
You can not pair more keys than the amount in the Central Convenience block.