What changes
Unit 17 (instrument cluster): long coding, byte 0, bit 0 = 1, byte 0, bit 1 = 1.
Details
Audi A4 B8 (8K). The map is compiled from public descriptions of the B8 coding and has not been confirmed by a write on a car. Odyx reads the unit's coding first and shows the changes. On early B8 cars the unit answers over TP2.0 (KWP2000) — you need an ELM327 adapter that supports TP2.0; on the B8.5 some units answer over UDS. To undo, use the write history.
Other options
This is one option of the “Gauge lighting with the headlights off” setting: only one can be active.