Hi, are there any Audi specialists that could provide some assistance on here? I have a problem with my 2019 Audi A7 (posting here for greater visibility) . After leaving it overnight or more than 4-5 hours, the brake pedal is rock hard and starting the car is difficult without lots of force on the pedal. This isn't an uncommon problem, I know many people have the same issue but most people seemed to be resolved by applying the fix as per the Audi TSB for replacement vacuum hose with non return valve. But I've replaced mine with the correct part, and the problem still exists.
Might anyone be able to point me in the right direction of where there are other common vacuum leaks in the system? I have put a vacuum pump on it and it does seem that something is loosing vacuum but I can't figure out where
Thanks