I have a 2004.5 S-40 with the OEM HID's. The left lowbeam HID began working intermittantly (ie. off at startup one day, on at startup the next). Now it won't come on at all and the bulb out message shows in the info center. Is this a bulb or a ballast problem? If bulb, what would be a good replacement bulb? If ballast, same question. Thanks for any help.

 

I would say ballast.
Not sure besides the Dealer.