For some reason it backfeeds the transmission or something - can’t remember the detail now!
But it’s a common error that crops up
Glad it’s fixed and cheaply
You need a CDU51L and according to wiring diagrams it is indeed bullet connectors for the reverse light switch.
The switch with the multi plug on is the first gear switch
Have you checked the brake light switches - doesn’t always flag a full DTC - there’s sometimes a fault stored in the error memory which is separate from the DTC memory and can be read with T4 but not sure of other diagnostic kit capabilities
The interior colour is known as alpaca.
I’ll check and get a part number for the reverse light switch - is it a 1.8 or a Td4?
What is the switch you have already?
In the settings menu on the headunit you can turn on/off the output for the rear speakers/subwoofer and have it via normal speaker connection - what setting have you got this on?
I assume all speakers and outputs worked ok on the old unit?
It tells you fault codes for the infotainment system and the configuration of the system and you can test the video inputs
It’s a lot cheaper then buying diagnostic kit to do the same job