Audi's flagship sedan on the MLB evo platform, pairing the EA839 3.0-litre turbocharged V6 with a 48V mild hybrid system, ZF 8-speed Tiptronic, and quattro all-wheel drive. Adaptive air suspension is standard on all A8 models. The dual-touchscreen MMI system debuted on this generation, alongside optional LIDAR-based driver assistance. Facelifted in 2022 with updated styling and software improvements.· more· less
Smooth, powerful V6 turbo engineExceptionally refined and quiet ride
Water pump design flaw (near-certain)Air suspension adds costly failure risk
Buy if: You want a refined flagship sedan for long-distance use and can verify the water pump has been updated to the revised 6-bolt unit.
Avoid if: You cannot budget for flagship-level repair costs or want predictable running costs without surprise air suspension or 48V system bills.
Vacuum-controlled water pump leaks internally, potentially damaging the vacuum system and causing overheating · more· less
The EA839 V6 has a well-documented water pump design flaw shared across Audi models using this engine. The pump uses vacuum-controlled impeller actuation with internal rod seals separating the vacuum chamber from the coolant passages. When these seals fail, coolant enters the vacuum chamber and can be ingested into the engine's vacuum system, potentially causing secondary damage. Symptoms include gradual coolant loss, P0299 drivetrain malfunction codes, and coolant residue visible on the left side of the engine. Audi released a revised water pump identifiable by its 6-bolt pulley (the original defective unit has a 4-bolt pulley). When replacing, specialists recommend also replacing the vacuum solenoid valve, coolant bypass valve, and associated gaskets. Independent shops charge approximately €1,200-1,800 for the complete job, while Audi dealers quote €2,000-2,500. Most failures occur between 80,000 and 130,000 km. This is widely regarded as a near-certain failure point on the EA839 engine.
48V belt starter generator (BSG) failure
up to €2,5002 of 8
Power transistors overheat or moisture enters, causing 48V system shutdown and battery drain · more· less
The 48V mild hybrid system uses a belt-driven starter-generator manufactured by Continental. The power transistors inside the unit overheat during normal operation, causing the electronic board to fail. When this happens, the 48V battery drains completely, followed by the 12V battery, which can leave the car immobilised. Symptoms include multiple dashboard warnings for the electrical system, start-stop, and brake booster. Audi has issued service campaign 27BQ affecting the A8 D5 alongside the A6, A7, Q7, and Q8. A specialist repair of the IGBT components costs approximately €200-800, while Audi dealers charge €1,500-2,500 for a full replacement unit including coding. Audi has extended warranty coverage to approximately 10 years from in-service date for this component. Early 2018-2020 models are most commonly affected. Always verify via VIN whether the service campaign has been completed.
Adaptive air suspension strut leak
up to €3,0003 of 8
Air spring bladders develop leaks, causing the car to sag overnight or trigger suspension warnings · more· less
The D5 A8 comes with adaptive air suspension as standard on all models. The air spring bladders deteriorate from UV exposure, road salt, and thermal cycling. When a bladder cracks or a seal fails, the affected corner sags, often noticeable after the car sits overnight. The compressor then runs excessively to compensate, which shortens its lifespan. A single OEM front air strut costs approximately €900-1,200 from Audi, with aftermarket rebuilt units available for €600-900. Labour runs approximately €300-500 per strut. Rear air springs are somewhat cheaper at €400-700 per side. The compressor itself costs €400-600 for the part. This issue typically develops between 100,000-150,000 km or after 6-8 years, though road conditions and climate influence timing. A recall for shock absorber faults affected models made between October and December 2018.
Carbon buildup on intake valves
up to €1,5004 of 8
Direct injection causes carbon deposits that reduce performance, typically noticeable after 80,000-120,000 km · more· less
Like all direct-injection petrol engines, the EA839 V6 accumulates carbon deposits on intake valves because fuel is sprayed directly into the combustion chamber rather than across the valves. Over time this restricts airflow, causing gradual power loss, rough idling, misfires, and increased fuel consumption. Walnut blasting is the only effective removal method. The V6 has six valves per cylinder (three intake, three exhaust), making the cleaning process more labour-intensive than on four-cylinder engines. Independent specialists charge €800-1,200, while Audi dealers quote €1,200-1,500 or more. Short trips and city driving accelerate the buildup. Occasional spirited driving and using quality oil helps slow buildup but does not prevent it. Budget for walnut blasting every 80,000-120,000 km as a near-certainty on higher-mileage cars.
MMI dual-touchscreen freezing or rebooting
up to €2,5005 of 8
Upper or lower touchscreens freeze, go black, or spontaneously reboot during driving · more· less
The D5 A8 pioneered Audi's dual-touchscreen MMI system, with the upper screen handling navigation and infotainment and the lower screen controlling climate and vehicle functions. Both screens can freeze, go black, or spontaneously reboot. In most cases this is a software issue resolved by a dealer update or a soft reset (holding the power button for 15 seconds). However, if the main computing unit (MIB3) fails internally, replacement costs €1,500-2,500 at a dealer. The rearview camera display can also stop working due to an internal hardware fault, which was addressed by a recall on some 2021-2022 models. A simple system reset fixes roughly 30% of all MMI issues. In the A8 specifically, the lower screen controls climate and seat functions, so a failure affects daily usability.
Front control arm bushing wear
up to €1,5006 of 8
Multi-link front suspension bushings deteriorate, causing clunking and vague steering after 80,000-120,000 km · more· less
The A8 D5 uses a multi-link front suspension with aluminium control arms. The rubber bushings deteriorate from road impacts, temperature cycling, and age. Symptoms include clunking noises over bumps, wandering at motorway speeds, and uneven inner tyre wear. Audi uses integrated arm assemblies where the bushing cannot be replaced separately, so the entire arm must be swapped. A full front control arm kit at an Audi dealer with OEM parts costs €1,200-1,500. Independent shops using quality aftermarket arms (Lemfoerder or Meyle HD) charge €600-900. This typically becomes noticeable between 80,000-120,000 km depending on road conditions.
LIDAR washer nozzle leaks and pre-sense sensor faults
up to €1,5007 of 8
LIDAR washer nozzles leak continuously, and pre-sense sensors can malfunction requiring recalibration or replacement · more· less
A8 D5 models equipped with the LIDAR-based driver assistance package experience washer fluid leaking from the front bumper LIDAR cleaning nozzles. The nozzles fail to seal properly and drain the washer fluid reservoir. Replacement nozzles cost approximately €30-50 each. Audi has released a software update for the laser scanner that optimises the cleaning algorithm to reduce washer fluid consumption. Separately, the pre-sense front radar and camera system can malfunction, triggering persistent warning messages. Simple sensor recalibration at a dealer costs €100-200. If the body control module, camera, or radar unit needs replacement, costs can reach €800-1,500.
Elevated oil consumption
up to €5008 of 8
Some EA839 engines consume oil faster than expected, requiring top-ups between services · more· less
Some owners report oil consumption of 0.5-1.0 litre per 5,000 km on the EA839, which Audi may consider within acceptable limits but is higher than many owners expect. In rare cases, consumption can be significantly higher, indicating possible piston ring seating issues. Regular monitoring and top-ups with the correct 0W-40 or 5W-30 synthetic oil are essential. If consumption exceeds 1 litre per 3,000 km, a compression test and cylinder leak-down test are warranted. The cost is primarily for additional oil between services.
Refined flagship, but water pump flaw and air suspension raise ownership costs
The EA839 V6 is a smooth, powerful engine used across the Volkswagen Group in models from the A6 to the Porsche Cayenne. The ZF 8-speed Tiptronic is one of the most reliable automatic gearboxes available. However, the well-documented water pump design flaw is a near-certain repair, and the standard air suspension adds a layer of complexity not present on the A6. The 48V mild hybrid system has its own recall history. Carbon buildup is inherent to all direct-injection petrol engines and will require periodic walnut blasting. Overall, the 55 TFSI can be reliable by flagship sedan standards when properly maintained, but buyers should factor in the water pump replacement as a planned expense and verify BSG recall status before purchase.
Service history
Complete Audi dealer or specialist records essential. Verify oil changes every 15,000 km or annually. The EA839 uses approximately 6.8 litres of 0W-40 synthetic oil.
Tires
Check tread depth, age (date codes), and uneven inner-edge wear that may indicate worn control arm bushings. Standard size is 255/45 R19.
Cold start
Start the engine completely cold. Listen for any unusual rattling, ticking, or metallic noises in the first 30 seconds.
Test drive
Minimum 30 minutes including motorway speeds and stop-and-go traffic. Pay attention to gearbox behaviour, suspension comfort, and dashboard warnings.
Specific for this vehicle
Identify water pump version (4-bolt or 6-bolt)
Check the water pump pulley bolt count. The original defective pump has 4 bolts; the revised pump has 6. If the car still has the 4-bolt pump, budget for replacement.
Check coolant level and for residue on engine
Low coolant, dried residue on the left side of the engine, or coolant buildup around the water pump area indicates imminent or ongoing pump failure.
Check for 48V system warnings on dashboard
With the engine running, verify no electrical system, start-stop, or brake booster warnings appear. These indicate BSG or 48V battery issues.
+ 5 more checksShow less
Verify BSG service campaign completed
Ask the seller or an Audi dealer to confirm service campaign 27BQ has been completed. This is critical for 2018-2021 models.
Test air suspension overnight if possible
Park the car overnight and check for sagging the next morning. Use MMI to switch ride height modes and listen for compressor noise or hissing.
Test both MMI touchscreens thoroughly
Operate the upper navigation screen and lower climate control screen. Test responsiveness, check for freezing, and verify the rearview camera displays correctly.
Monitor oil level on dipstick
Check the oil level carefully. If it is near or below minimum, ask about consumption history. Excessive oil use may indicate piston ring issues.
Test all driver assistance systems
Verify pre-sense, adaptive cruise control, and parking sensors function without persistent warnings. Check washer fluid level for LIDAR nozzle leak signs.
Recalls and Technical Service Bulletins
Belt starter generator (BSG) power transistor defect causing 48V system failure (2018-2021 models, service campaign 27BQ)Critical - verify completed
Shock absorber defect (models produced October-December 2018)Verify completed
Front passenger seat rail fastening (models produced January-March 2019)Verify completed
Gearbox oil line leak (models produced September-December 2019)Verify completed
Active headrest malfunction (models produced January 2018)Verify completed
Rearview camera display failure due to infotainment unit hardware fault (2021-2022 models)Verify completed
Contact an Audi dealer with the VIN to verify all recalls and service campaigns have been completed. The BSG campaign (27BQ) is particularly important for 2018-2021 models, as it can cause a complete vehicle shutdown while driving. The rear axle lock nut recall (42L1) is safety-critical. The shock absorber recall only affects a narrow production window (October-December 2018).
Warranty Status
Factory warranty (2 years, no km limit)Expired on most used D5 models
BSG extended warrantyApproximately 10 years from in-service date
Rust perforation warranty (12 years)Still active on 2017+ cars
Extended warranty (Audi Garantie)Available through Audi dealers
Most used A8 D5 models are outside the standard 2-year factory warranty. However, the belt starter generator has extended warranty coverage of approximately 10 years from the in-service date due to the known defect. The 12-year rust perforation warranty still applies to all D5 models. Audi offers extended warranty packages through dealers for cars up to 10 years old and 150,000 km.
Sources: Research draws on model-specific owner forums and owner communities, recall information from official authorities, German automotive press, and multiple workshop cost references cross-checked against each other.
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.
