I had the drivers side low beam factory HID headlight fail. Tbelieving I had a bulb problem I ordered a set of replacement D2S off EBAY. I installed the new bulb and presto! Still no beam light. (The original factory bulb I took out looked OK to me).

My question is: Could the ballast be the failed component? How can I trouble shoot the culprit?

 

Could be the ballast, take the original bulb you removed and place it in the other other headlight.. see if it works.. Also even the new bulb.. could be both the bulb and ballast that failed.. Can even try the working bulb on the other side with the culprit ballast. See if any of that works.

 

I placed the passenger side working factory D2S bulb in the driver's side headlamp assembly and no light. I placed the new bulb in the passenger headlamp assembly (I had placed this bulb earlier in driver's side headlamp assembly with no success) and I have light. I am convinced it must be the ballast. I forgot to mention the headlight warning was activated on the Audi counsel message center.
Where can I obtain a factory replacement ballast other than contacting an AUDI dealer?

 

Sounds like it is indeed the ballast.. I found this on ECS.. it's expensive.. don't know how much it is at the dealership.. but i'm sure more than ECS.. they're usually a bit cheaper.. I would check the marketplace here.. on VW vortex.. and audizine.. look for a part out.. might have to just buy the whole headlight with ballast and bulb.. but i've seen all of that cheaper than the ballast price on ECS.. goodluck!

Audi B5 S4 2.7T > Lighting > Headlights > ES#252655 B5 S4 HID Igniter - Priced Each - 8D0907391A

 

Hey, evelusser from the forums is selling a set for 100 bucks. Nab it man! i replied on the thread that you'd probably be interested.. told him to pm you if you don't pm him first. here's the link.. awesome timing.

https://www.audiforums.com/forum/ext...7/#post1323832