While I was at a dealer having some repair work done I asked them to reprogram one of my keys. I have had 2 keys that worked and 1 that turned and lit the dash, but would not start the vehicle. One key I keep in the car ash tray w/o a keychain because I don't like how it dangles and hits my leg. Anyway... the dealer reprogramed 2 keys with the computer, but not that one. When I picked up the car they key that didn't used to work now did, but the one in the car that I used every day did not work. Someone came out from the back and put the first good key into the ignition and turned it to run, took it out, put the next one in to run, took it out, and then put the non-programmed one in and started the car. This worked. However, after taking the newly programmed key out and attempting to start again, it would not. It only lit up the dash as a non-programmed key would do. They attempted again and same thing.
The shop guy told me the chip was bad in the key. If you shake the key you can hear something inside it rattling and he told me this was the chip.

Does anyone know if there is any truth to this? I have been using this key for 1 year with no incident, and it has rarely, if ever left the car. Furthermore, I had an XK8 for 5 years prior to this car with no key/chip issues, my brother has had 2 XK8s and my father also has one. None of them have every had a issue with the chip in a key and it is not a common topic on these forums. I am thinking that they just didn't want to reprogram all three with the computer? Any thoughts?

 

I'm going to try and think like the car for a sec.

You use a key that was programmed, the security recognizes the chip, the key is correct to the ignition barrel, fires up.

Within seconds, the next programmed one, works just fine.

Next un-programmed one, within another 10 seconds, and it also works.

Perhaps, the first key 'passed' the security screening, and the other non-programmed key used the first key's 'clearance' to start the car.

Now, after sitting awhile, the security protocols resets itself, and the un-programmed key cannot pass the security module screening.

To confirm, try it again, one key after another. Arm/Disarm after each key. I bet the last, un-programmed key still won't work in quick succession.

I would bet it just needs programmed again (all 3 together)...but that's gonna cost you a dealer service charge again.