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ponsaloti, please can you confirm something for me.
AIUI, there's a key difference (if you'll pardon the pun) between the approach taken by Fiat dealers, and the approach taken by aftermarket auto locksmiths.
The official way is to order a key and then program the car to accept that key, together with any other keys that are in the possession of the owner. This process requires Examiner & the electronic keycode and will prevent any other keys that may previously have been programmed to the car from deactivating the immobiliser. Essentially this erases any previous key information from the body computer and you are starting with a clean slate. For this reason, if you order an additional key from a main dealer, you have to give them all the keys in your possession so that the car will continue to recognise them.
The unofficial way is to interrogate the car to obtain the necessary information from the body computer to program a transponder in the key. The disadvantage to this method is that any working keys not in the possession of the owner will still work (the security implications of this are obvious). This doesn't need the keycode, as sufficient information to program a transponder can be obtained from the ECU. This is presumably a calculated hash total; I can't believe the keycode is directly retrievable from the ECU (that would be appaling cryptography).
So in summary Fiat will program the car to the keys; the aftermarket will program the keys to the car.
Any further information from those who actually know what they are talking about would be greatly appreciated.