[Tannaton]

Yes it will throw an error as there is a dedicated computer to operate the headlights and it won't be happy.

The electrical switching is very different between halogen and Xenon as well.

If you search on here there is an article on how to strip the headlights down (to fit LED DRL's) you may be able to clean the reflector and lens.

I feel your pain - they are obscenely expensive.