I have a 2006 Audi A4 2.0T S-line with the adaptive, xeon headlights. For the last couple of years I have been losing my passenger light and getting the headlight dipped error message on my driver's information screen. It would flicker and then go off. I would turn the lights off and then put them back on and it would work for a while. sometimes it would be okay for a week. Other times it would continue to go out all night long. It is worse in the cold weather. This year it was getting really bad so i know i had to do something. i researched a couple of threads and found that headlight dipped is basically the default error message for many headlight errors but it was recommended to start with replacing the bulb so that is what i did.
The dealer wanted $160 for a replacement bulb so I sourced one locally for $75. It is a DS1 model (not the DS2). Fortunately, I was replacing the passenger side which is supposedly the easier of the two. Following instructions on the other threads I ran through the job and after a week since I did the repair, my headlight has had no issues so I'm officially calling the problem fixed. here is what I did:
Disconnect the battery
Remove upper air intake housing
Remove air cleaner hose and push to the side
Remove entire air cleaner housing. Mine had some wire/hose attachments taped to clips mounted on it. I had to cut the tape to free the housing. It is held in from the bottom and the side but just pulls out.
I cleaned the area underneath.
i opened the headlight assembly access door
Removed the two metal clips that hold the bulb
Disconnect the new bulb from the wiring
Install the new bulb (don't touch the bulb)
Put everything back together.
The job wasn't bad at all. the only special tools was the torx screw driver for the headlight access door (two screws).
The dealer would have wanted $400 for this repair. If you have this issue you can do this.
Sorry for no photos but here are the two links I used which do have photos.
How to Fix Dipped Headlight Error on an Audi ? Nick's Car Blog
DIY: HID headlight bulbs replacement without removing the front bumper