i have a 2000 s430. i am changing the halogen to xenon. the xenon light assemblies are oem. what type of reprogramming is required? can i do? is it only a mercedes dealer thing?

There is also a control unit for keeping the xenon lamps adjusted properly. The name of the system is HRA-Headlamp Range Adjustment. If you only have the lamp assemblies you don't have enough to make it work properly. I also believe the wiring harness is different if you have xenon lights.

Gilly

I have done this before. the lamps just plug in and work.
You will not have HRA (auto aiming) like Gilly said, but the lamps
will work just dandy. The only draw back is an occasional "Check front lowbeam" message that may pop up in the cluster from time to time. Usually in cold weather.

DON'T FORGET to aim these darn things correctly and low, to avoid dazzling oncoming drivers.

Dr.D

can the HRA be added? if so, is it complicated?

Big job! requires retrofitting a HRA control module under pass floorboard and installing a large wiring harness to the l/f fuse box
as well as to all along the underdash area.
Not as bad as previous vehicles since you car allready has body sensors for height as part to the air suspension system.
Still pretty labor intensive job. I would plan on 2-3 thousand
dollars just to start.
Most people just put in the headlamp units and call it good.

Dr.D

p.s. I have a set of 220 s-class xenon lamp units. they could be for sale if interested. let me know.