Reverse gear problem Audi A4 8D 1.8T Multitronic, first registration 03

Unfortunately, I couldn't find a suitable answer in the forum.
The Audi sometimes fails to shift into reverse. However, the following procedure often works: Put the car in neutral, turn off the engine, restart it, and then it usually shifts into reverse.

'The following error occurred:'

17090 Step sensor (F125) - implausible signal.
P0706-35-00--

Are there any known issues? Is it possible or necessary to replace the sensor?

hello,

You'll probably need a new transmission control module; the sensor is located inside it, as far as I know.

btw: your A4 is an 8E (the 8D is the previous model).

That doesn't sound good at all.
Is it possible to confirm the suspicion using VAG-Com (I have entered the serial number in my profile)?
I'm not very good with electronics; I'm a mechanic specializing in engines.