I have been having the same problem (53 plate IS200), i have been losing the keys at a steady rate to the point where my last remaining key was washed and only works some of the time.
I have been buying spares off ebay and now have quite a collection of uncut blades. Got a local shop to cut one (works in the ignition but not the doors) and tried to program it in using the various steps. Tried for ages with the transponder from ejaz0### from ebay with no luck. Tried another transponder from another supplier and have got half of the way there.
Take a look at the transponder, once you open the case, the correct ones need a scredriver to reveal the battery, and use a 1616 battery. If it says 'Valeo', probably will not work.
By half of the way, I mean, I can now get the car started but no luck with the remote programming. My progress is as follows:
1. Close and lock all doors. Unlock and open drivers door. DONE
2. Put key into ignition and remove. Do not turn it on. DONE - THIS IS THE MASTER KEY..
3. Using the electric lock switch. Lock and unlock 5 times. (Lock, Unlock, Lock, Unlock, Lock, Unlock, Lock, Unlock, Lock, Unlock) DONE
4. Close and open drivers door. -DONE
5. Using the electric lock switch. Lock and unlock 5 times. (Lock, Unlock, Lock, Unlock, Lock, Unlock, Lock, Unlock, Lock, Unlock) DONE
6. Put key into ignition. Turn to "ON" , turn off and remove. DONE - THIS SHOULD BE THE MASTER KEY
7. You will see the door locks cycle by themselves. - YES THEY DO!!
If the door locks do not cycle (lock and unlock) by themselves then the car isn’t in programming mode and you must start over.
8. On the remote, press and hold the LOCK and the UNLOCK button at the same time for no more than 2 seconds. -NOTHING HAPPENS
9. On the remote, press the LOCK button for no more than 1 second. - NOTHING HAPPENS
I have tried standing outside the car, quck presses, slow presses, everything (I think).
Give me some ponters, please!!!!
Also, a youtube vid would be much appreciated!!