Audi S6
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 5
On vehicles from model year 2018 the panoramic roof can detach due to adhesive bond failure. Audi issued a recall; confirm completion before purchase.
The 48V belt-driven starter-generator (BSG) is a known weak point of the C8. When it fails the entire 48V electrical system goes offline. Audi granted an extended warranty of 7 years on the component.
On some C8 models moisture enters through a leaking wheel arch and causes a musty smell inside the vehicle as well as possible corrosion on electrical components.
On the S6 C8 the adaptive cruise control (ACC) and MMI infotainment system drop out sporadically. The automatic emergency brake triggers too early. Primarily affects 2018–2021 models.
The S6 C8 with 450 hp and a 2,000 kg kerb weight places heavy demands on the braking system. Spirited use leads to frequent brake disc replacement, especially on the front axle.
Reports & Tests
6 owner complaints filed with NHTSA (2018–2026). Most reported: Electrical (3), Steering (2), Wipers & Visibility (1).