This bulletin applies to 2018-2021 Audi A5, Q5 and SQ5, 2019-2021 RS 5, 2017-2021 A4, S4, Q7 and SQ7, 2019-2021 A6, A7 and Q8, 2020-2021 A6 allroad, S6, S7, RS 7, SQ8 and RS Q8 and 2021 A6 Avanti and RS 6 Avanti vehicles.
After a short stationary period, the vehicle may sporadically not start and there is a hard brake pedal concern.
Due to dirt particles in the non-return valve in the vacuum hose for the brake servo, the vacuum in the brake servo cannot be held on a parked vehicle. When starting the engine, the usual brake force is not enough to get the start authorization of the brake light switch. Normally a vacuum of 600 to 950 mbar is reached. Depending on the parking position (slope) or the user behavior, the vehicle may be parked with a small vacuum. Within 12 hours the vacuum may drop by up to 400 mbar.
Replace the vacuum hose with a non-return valve and pressure sensor (G608) according to the Elsa repair manual.
