Hi all, firstly thanks to all for their contributions on this thread to help highlight and fix this very serious issue. Some background information. I am based in Ireland and in 2017 bought a new A5 coupe 190bhp 2.0 TDi from an Audi main dealer here - this car has always been serviced through this dealer.
With regard to this brake servo restricted issue I have been more fortunate than others and their experiences. The warning message first appeared in September 2021 (though with no accompanying start / stop function warning). However, this fault message disappeared after a few days and had been intermittent over the following weeks leading me to believe there was a loose connection somewhere. In early December the warning appeared again along with the stop / start function warning. Not realising the significance of continuing to drive with these warnings thankfully I only did limited mileage (this not by design) and yesterday I finally "googled" the issue. It was only through this forum / thread did I realise the potential to cause damage to the ABS system with a possible repair bill of €4,000+.
So as of yesterday evening I stopped driving the A5 and this morning I rang my local Audi dealer to order the brake pressure sensor hoping they would have a unit in stock. They did (cost = €107) and all I had to do was mention the part and the guy knew exactly the part number I required - so obviously a wide spread issue with Audi ! It took less than 5 minutes to change out the old sensor for the new and on starting the warnings were gone with standard brake foot pedal pressure restored.
My advice is similar to others on this thread - don't ignore the warning and you can easily replace the sensor yourself without resorting to Audi garage for high labour and diagnostic review costs.
Thanks again to all the contributors here ...........
