Thanks Gregory. I have a replacement key on the way which I'll test against my existing FZV, and if it doesn't work I'll order a replacement FZV module. I really appreciate the suggestion.

And, yeah... there just seems to be an awful lot of endemic replacement issues on the X5 compared to other vehicles I've had. I mean, even my Porsche 996 convertible didn't spit up parts with the regularity that the X5 does. It's such a great vehicle when it's running properly (in fact it's my favorite of all the ones I've ever owned) but man it requires a lot of maintenance.