Re: Sorry, but anyone got up to date KEY info
This is quite an old thread which I'm bringing up again because I've just gone through a CODE light problem with no master key.
It is impossible to program a master key unless you have it already. No matter how many copy keys you have you cannot get the master. If your car 'loses' the code for one key, it 'loses' all of them except the master.
If you're genuinely worried then you need to get your ECU virginised with a new code and new master key, then reprogram your existing keys to the new master key and code. Alternatively get an ECU with a rolling (ie no) code, and no immobiliser. I suggest doing this before you have the problem because if you wait for it to happen you lose the chance to choose when it's out of action.
A company called Camco 88 in warrington can do both of these things. (probably others can aswell, but they're the only one I know of).
For what it's worth my car lost it's code and I repaired it by disconnecting the immobiliser box under the steering column and applying a voltage across it, thus resetting it. Then resetting the ECU by pulling the fuse. Put the whole thing back together and the car remembers the keys. No need for master key.
I don't know when you would ever need the master key, unless you want to cut new copies. But I'm no expert