Mercedes-Benz W212 xenon and bi-xenon headlight faults
W212 xenon light not working or changing colour, what is wrong?
A reddish tint indicates the bulb is reaching the end of its life; replace both bulbs then. If the light does not work at all, the fault may be in the ballast (the igniter unit that regulates the bulb's current). A bulb can also break the ballast.
What kind of bulbs belong in the W212 xenon lights?
The xenon bulb is type D1S; H7 is a halogen bulb. Use 35 W bulbs, not 55 W, because the ballast is rated for 35 W. Cheap bulbs fail quickly. The bulb can be replaced through the wheel arch and the wing, and the battery does not need to be disconnected.
Why do the bi-xenon lights point too high or too close?
The cause can be a detached height adjustment rod at the front left by the lower control arm. Reattaching the rod fixes the problem. The original plastic rod is 13 cm long and has 14 mm ball joints at the ends. The headlight aim is set according to the instructions.