Upholstery dude uses adhesive in a can never in a spray, those who have large workshops compressor and spray gun, so if you do the roof upholstery yourself, buy glue in a can , it's a orange or rust color of the famous scent
I do not know how it is in Poland , but in Croatia with a couple of companies where you can buy textiles for auto industry , and upholstery guys sell the same upholstery material as OEM , so you can get everything and do it yourself, maybe change to black.
You can also insert the starry sky yourself, you have to buy on AliExpress link , something like this . ,
You can make some constellations and stars around or galaxy , measure the roof, take it to a bookstore or who already has big printers, let your print constellation in the dots and transfer it to the roof. D .
When the upholstery is over, you pierce the fabric and cut off the excess, pierce the roof before placing a new fabric.
ABS light can be like you said sensor , but it can be a bed wheel bearing , i had abs and esp light , it wad on the left rear wheel i replace the 2x sensor and bearings on rear side , because sooner or lather it will be gone because its old car , but i love it
I like the car , i think someone take care of it , there is a few scars from the old age , just little ones
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What kind of color is your car , i think i have never seen that color on any Audi , it's like some kind of light , light coffee with milk color
Countless happy kilometers with it.