I type too much so I'm summarizing this into a TLDR:

0. 2006 A8L 4.2L new purchase
1. Light/rain sensor worked for about an hour
2. Changed VCDS instrument coding to disable airbag chime
3. Auto lights no longer work. Auto wipers do work.
4. Reverted VCDS changes - did not repair issue

5. Any help is appreciated. I feel like the sensor is functional- but this code is pointing to some type of adaptation. I cannot access the adaptation section of 09 - central electric - it is grey'd out???


Address 09: Cent. Elect. Labels: 4E0-910-279.lbl
Control Module Part Number: 4E0 910 279 Q HW: 4E0 907 279 Q
Component and/or Version: ILM Fahrer H14 0230
Software Coding: 0143123
Work Shop Code: WSC 02313 785 00200
Additional Info: 4E1910113B Wischer WWS D3 H50 0400 4E0910557A REGENLICHTSENSORH12 0090
VCID: 3663C05341B2A6AE7EF-8063
1 Fault Found:

01520 - Rain and Light Recognition Sensor (G397)
005 - No or Incorrect Basic Setting / Adaptation - Intermittent
Freeze Frame:
Fault Status: 00100101
Fault Priority: 3
Fault Frequency: 32
Reset counter: 76
Mileage: 195373 km
Time Indication: 0
Date: 2018.08.19
Time: 20:49:27

Long story with full details if anyone cares:

I just bought a 2006 A8L 4.2L and have an issue with the light and rain sensor.

I drove the car for about an hour with the automatic headlights fully functional - along with automatic wipers. It was raining during the day and the lights came on as they should have. During that drive I had a CEL pop up and pulled over. Took out VCDS and read the code (motor related and unrelated to this thread). While at it I disabled the airbag chime as well by changing the coding for the instrument cluster. Upon starting the car the headlight error immediately came on, but the seatbelt didn't chime.

Since then the only other VCDS mod I have done is:
65-tire pressure system coding: Original: 0232125
changed to: 0202125 - this was to disable TPMS until solving sensor issue

I have tried restoring the airbag chime and TPMS back to the original codes (both of which I took note of).
I have went into the deeper coding module specifically for the rain/light sensor and used the VCDS wizard to modify the hex to change glass types and sensitivity. No luck.

The weird part is the rain sensing wipers work close to perfectly. Just have an issue with the automatic lights and only when I turn the switch to the auto feature.

Has anyone ran into this???