Audi S6 Avant
EA839 BiTurbo V6 with 331 kW for S6/S7 C8. Switch from V8 to V6 compared to the predecessor, but with 48V mild hybrid and electric compressor, performance is nearly identical.
V6 replaces V8 — quick, efficient, nobody asked for it
They killed the V8 and replaced it with a V6 and a 48V system. Quick? Yes. Efficient? Yes. Nobody asked for this. The C7 with its twin-turbo V8 is climbing in value while C8s sit at dealers. Three of four C8 buyers on Audizine traded for an S8 — the only way left to get a V8 in the S-range.
Engine Weaknesses 5
Small roller bearings in the rocker arms can detach and fall into the oil pan. Affects 2.9 BiTurbo engines from early production (up to approx. 2019, code GP0). Revised rocker arms (GP1) introduced from 2017.
Symptoms: Knocking noises from cylinder head, engine roughness, misfires, metal particles in the oil
The upper timing chain tensioners of the 2.9 TFSI tend to weaken. Typical rattling on cold start that disappears after warm-up. Audi revised the tensioners; goodwill repair often possible.
Symptoms: Rattling on cold start (2,000–3,000 rpm), disappears after warm-up
The DCTB 2.5 TFSI Evo (RS3 8Y, 400 hp) shows early high-pressure pump failure on some examples. Power loss and misfires are typical symptoms.
Symptoms: Power loss under high load, rough running, fault code fuel pressure control, increased fuel consumption.
Direct injection without port injection leads to carbon deposits on intake valves. Power loss and increased consumption from around 80,000 km. Walnut blasting required.
Symptoms: Power loss, rough idle, increased consumption, poor cold-start response
BiTurbo wastegate linkage rods can wear and produce metallic rattling on overrun. Known on the EA839 BiTurbo. Repair often only possible by replacing the turbocharger.
Symptoms: Metallic clattering when lifting off throttle, especially during spirited and motorway driving
Vehicle Weaknesses 6
Contamination of the bonding surface during manufacture can cause the rear panoramic roof module to detach. Affects A6 models produced in 2018.
On the A6 Avant (MY 2018), the rear glass panel of the panoramic roof was incorrectly bonded. Audi recalled 1,435 vehicles in Germany. Creaking/scraping noises and water ingress are further known issues with the panoramic roof.
Stress corrosion cracking can cause excessive play between the control arm and wheel carrier on the A6 C8 (MY 2019–2021), impairing driving stability. Recall by KBA (action 42L1), free repair at dealer.
High-voltage battery cell modules on A6, A7, Q5 PHEV models can overheat during charging (KBA 15722R / code 93AD). 53,449 vehicles worldwide, 17,012 in Germany affected (production period 08/2019–08/2024). Software update takes approx. 60 minutes.
The MMI infotainment system stands out for frozen displays, unexpected reboots and Apple CarPlay/Android Auto failures. Software updates only partially resolve the problem.
On some A6 C8s, water enters through a leaking wheel arch liner, causing musty smells and moisture in the footwell or boot.
Reports & Tests
145 owner complaints filed with NHTSA (2018–2024). Most reported: Electrical (108), Engine (29), Collision Avoidance (18).