Adaptive Headlight Defective - Troubleshooting

[MacaveliMC]

Ever since I bought the car (end of Nov 2020) I've had this adaptive headlight defective error pop up every time I drive the car. I had plenty of other things I wanted to do on the car and my headlights still both "worked", so I ignored it for a while. But now I'm getting ready to diagnose it. So here are the details:

The error pops up pretty much every time I drive the car. If there was any time it didn't, I didn't realize it but it was definitely the exception.

Sometimes it pops up within a couple minutes of driving, sometimes it pops up after I've been driving for a bit, and sometimes it pops up right before I get where I am going. Basically, I haven't found any way that it's reliably repeatable. Nothing specifically seems to cause it as far as driving, turning, ect. Knowing this, I would tend to believe it's not a broken wire inside the headlight housing, because if it was I'd assume the error would pop up immediately all the time. Maybe a loose connection? Swivel motor going bad? Ect.

Here is the error code from VCDS:

Address 55: Headlight Range Labels: 8T0-907-357.clb
Part No SW: 8H0 907 357 C HW: 8H0 907 357 C
Component: AFS 1 H01 0040
Revision: 00H01001 Serial number:
Coding: 0000020
Shop #: WSC 06324 000 00000
VCID: 323D116D5823FBABB56-8066

Subsystem 1 - Part No: 8K0 941 329
Component: AFS-Modul links H02 S001

Subsystem 2 - Part No: 8K0 941 329
Component: AFS-Modul rechtsH02 S001

1 Fault Found:
02769 - Headlight Swivel Module; Left
003 - Mechanical Failure - MIL ON
Freeze Frame:
Fault Status: 11100011
Fault Priority: 2
Fault Frequency: 1
Reset counter: 40
Mileage: 169412 km
Time Indication: 0
Date: 2020.10.16
Time: 18:04:52


The reason I'm posing about this, is because I have very limited time at the moment (newborn household going on 2.5 weeks) to work on car stuff, so I need to be as quick and efficient as I can be. If I get the headlight off the vehicle, what should I be looking for to diagnose the headlight and figure out what may be the issue?

EDIT: or is it not worth it, and I should just buy this? https://www.ebay.com/itm/2009-2012-Audi-A4-S4-Left-LH-Driver-Xenon-HID-Headlight-Complete-OEM-09-10-11-12/393015865596

Thanks for the help!

[Smac770]

Since you have VCDS, I would go into the J519 (central electrics, address 0x09) output tests and see if there are any for testing headlamp movement (range control up/down and AFS left/right). That's the only diagnostic stimulus I can think of to try.

There's one motor (V48 left, V49 right) built into the HID headlamps to do up/down range control, and two additional motors (V318 left, V319 right) built into the HID+AFS headlamps to do left/right swivel. While your DTC implies the V318 swivel motor, it doesn't specify it directly. Still, whichever motor it is, neither of those are separable from the headlamp housing. Or at least not meant to be. I'm sure with tools you can cut apart anything. But do they just need servicing, or replacement. And where would you source a replacement as they are not available from Audi. So you'd be sourcing a whole headlamp anyway.

That eBay listing has no explicit part number stated. The sticker posted is showing the part number for the headlamp housing component, not the composite headlamp assembly which Audi sells. The left headlamp will be 8K0 941 029 xx as Audi sells it, where there's lots of inputs to dictate the correct "xx" revision letter(s). The left headlamp housing component part number is that 8K0 941 003 that you see in the listing. That one is "R". R would be a HID, without AFS, headlamp for a US spec B8.0 A4/S4 built after Jun 21, 2010. R was superseded by AS at some point.

For a left side HID+AFS headlamp for a US spec B8.0 A4/S4 built after Jun 21, 2010, you'd be looking for 8K0 941 029 AA, now superseded by BB. It's likely that you might find listings for 8K0 941 003 AA or BB if that's the part number they are finding on the housing sticker. You can know, for B8.0, that it's AFS because it'll have the control module, or plug as this example seems to be gutted of the three electronics modules, on the bottom side: https://www.ebay.com/itm/Driver-Headlight-Station-Wgn-Xenon-HID-Adaptive-Curve-Fits-09-12-AUDI-A4-15826/133583010044

[MacaveliMC]

Hmmm, thanks for the detailed response. I'm gonna have to spend more time studying this, and figure out how to get a new/used headlight, with all the parts in it.