Audi A8
4.0-litre TFSI V8 with 435 PS (EA825) in the A8 D4. Turbocharged V8 with cylinder deactivation — eight cylinders under full load, four at part throttle. Oil strainer contamination and high-pressure pump pressure piece wear are known weak points. Regular short oil change intervals (10,000 km) are mandatory for longevity.
V8 BiTurbo — understatement with bite
435 hp V8 combines comfort with track potential. Perfect camouflage for genuine performance.
Engine Weaknesses 5
A fine oil strainer in the turbocharger oil supply line clogs with combustion residue. The turbocharger is starved of oil and seizes. The oil strainer sits in a difficult-to-access location inside the engine.
Symptoms: Sudden power loss or engine stall on the motorway without warning, whistling turbo noises, smoke, vehicle will not restart.
The camshafts of the 4.0 TFSI V8 are matched to cylinder heads in pairs at the factory. On wear, replacement is very labour-intensive as the camshaft and head must always be replaced together.
Symptoms: Rough engine running, engine warning light, rattle from the cylinder head area, power loss, elevated oil consumption.
The 4.0 TFSI V8 is not free of timing chain problems either. High-performance use and delayed oil changes promote chain wear. Repairs are very labour-intensive due to the twin-turbo architecture.
Symptoms: Chain rattle on cold start, engine warning light, camshaft position fault codes, rough running.
The complex electronics architecture of the S6/S7/S8 with 4.0 TFSI leads to expensive diagnostic and repair processes. Not all Audi dealers are authorised for high-performance models of this generation.
Symptoms: Sporadic warning messages from various control units, failure of individual comfort functions, unexpected behaviour of start-stop and cylinder deactivation.
Above 2,500 rpm the piston cooling oil jets of the 4.0 TFSI activate. During spirited driving, some oil burns off. Consumption can vary significantly but is design-related.
Symptoms: Oil level drops noticeably after spirited motorway driving, no smoke or smell, warning light only with severe consumption.
Vehicle Weaknesses 13
The adaptive air suspension on the A8 D4 is a well-known money pit. Air bellows become porous, the compressor runs non-stop and overheats. Repairing all four corners costs several thousand euros.
The 4.2 TDI V8 in the A8 D4 has a timing chain that is prone to premature wear when neglected. A break causes severe engine damage. Replacement requires complete engine removal.
The 4.2 FSI V8 has four timing chains with phenolic resin guide rails that become brittle with age. Neglected oil changes risk chain skip.
Turbocharger bearings can wear and bring the turbine wheel into contact with the housing. Audi recalled around 26,000 vehicles in 2022.
Leaking air bellows cause the vehicle to sink and force the compressor into continuous operation until it fails. Front and rear are equally likely to be affected.
The MMI multimedia system stands out from 60,000–100,000 km with frozen screens and unresponsive controls. Multiple control modules can be affected.
The ZF 8-speed automatic shows harsh gear changes and gear selection problems at high mileage. Regular oil changes (every 80,000 km) are critical.
The MMI multimedia system is known for total failures caused by overvoltage damage after battery replacement or moisture damage to the Bluetooth control module.
The rubber-metal bushes of the front control arms on the heavy A8 D3 show significant wear at high mileage.
Front and rear control arm rubber bushes go soft with increasing mileage. The A8's considerable weight accelerates wear.
The 6-speed Tiptronic shows harsh gear changes at high mileage. A gearbox oil change often resolves the problem.
With increasing age the driver's side window regulator switch block on the A8 D3 frequently fails. The switch block must be completely removed for replacement. Pixel failures in the instrument cluster and screen faults are further typical age-related symptoms.
Almost all A8 D3s show worn and peeling soft-touch surfaces on light switches, trim panels and control knobs. The coating detaches in strips, leaving a sticky surface that is visually badly affected.
Reports & Tests
124 owner complaints filed with NHTSA (2010–2017). Most reported: Engine (78), Other (13), Fuel System (12).