W211 2006 E320CDI bi-Xenon lights keep breaking

Page may contain affiliate links. Please see terms for details.


Active Member
Jul 4, 2009

Problem started about a year ago due to accidental damage.

Second-hand lights assembly was purchased and fitted. The fitment was not perfect in a sense that gaps between the lights and bodywork were a bit larger than on the side that did not have issues.

Within about 2-3 months the Xenon light stopped working. This was fixed by swapping the ballast to the one that was from the old, broken lights assembly. At that point it was noticed that the cap covering the HID bulb was not installed - it was on the bottom tray of the car. I assumed that the non-specialist mechanic who installed the lights did not put the cover properly. The specialist mentioned that moisture is very harmful to these lights.

Within another couple of months the Xenon light stopped working again, but then resumed, before I looked into the matter.

About a month later it stopped working again. When I looked into it the cover was again on the bottom tray. At this point I think it is unlikely that two mechanics, including one specialist would not put the cover properly. I can see some condensed moisture within the lights.

My ideas on fixing:
1. Try to buy some kind of small hair drier or something like that to direct heated air into light assembly to dry it out.
2. Try to buy some moisture absorbing silicon granules to place into lights assembly to further dry it.
3. Buy ballast on ebay - hoping chnaging ballast will fix it as the previous time.
4. Use very sticky tape, etc to secure the cap.
5. Put some sort of seal between the lights and bodywork so that rain water / carwash water does not get into so easily into engine compartment in the lights area.

Any advice on what else / different I could do to diagnose or fix the problem? How likely it is to be the ballast again (relatively cheap and easy to replace) rather than something within the lights assembly (expensive and difficult to replace)?

Users who are viewing this thread

Top Bottom