If you are considering buying a used Audi A8, these are the common problems worth knowing about first. Our garage database tracks 3 known faults for this model, 2 of them rated high severity. Every one below is a repair bill a seller has good reason not to mention.
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Is the Audi A8 reliable?
The Audi A8 has 3 known faults in our database across 2 generations, 2 of them rated high severity. The most serious are engine (timing chain tensioner failure causing severe rattling) and gearbox (the first-generation A8 was said to have had a run of failures involving the electronic). None of them makes the car a bad buy on its own; the risk is a seller who knows and says nothing.
That is a count of the faults we hold, not a reliability score. Popular cars get written about more, and a newer generation has had less time to show its faults.
Which Audi A8 years should you avoid?
No year is a write-off on its own. What matters is which serious faults a given year and engine can have, and whether the car in front of you has had them fixed.
1994 to 20031 high severity
1 known fault, the serious ones in the gearbox
2003 to 20101 high severity
2 known faults, the serious ones in the engine
Years and engines with a serious known fault
2004 to 2018, 3.0 V6 TDI (chain tensioner): timing chain tensioner failure causing severe rattling
1994 to 2003, Tiptronic automatic (all engines): the first-generation A8 was said to have had a run of failures involving
Each one is set out in full below, with the symptoms, the typical mileage and a rough repair cost.
Generation 1 of 21 known fault · 2 good notes
Audi A8 (1994 to 2003) problems
Transmission/ClutchHigh severity📝 Editorial
The first-generation A8 was said to have had a run of failures involving the electronic control unit and the Tiptronic automatic gearbox. No mileage, cost or cure was given.
Typical symptoms
Automatic gearbox failing to change gear properly
Gearbox or engine warning light on the dash
Affected vehicles
Engines:
Tiptronic automatic (all engines)
Typical mileage:
unknown miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
What owners like
2 notes
The A8 features an advanced all-alloy space frame body, offering a lightweight yet spacious construction for its size.
The 4.2 V8 engine provides high quality, quick, and luxurious performance, with the S8 offering even greater power.
Generation 2 of 22 known faults · 10 owner reports · 4 good notes
Audi A8 (2003 to 2010) problems
Engine/EmissionsHigh severity📝 Editorial
Timing chain tensioner failure causing severe rattling; chains are located at the rear of the engine, requiring engine removal to fix. This is wear in the tensioner and chain drive itself, which is a high mileage failure, and is a separate job from the camshaft wear reported on the C7 A6 Allroad at much lower mileage
Rough guide
£2000-4000
Typical symptoms
loud metallic slapping/rattling from the back of the engine on cold start
rattle persisting for more than 3 seconds
engine management light
Affected vehicles
Engines:
3.0 V6 TDI (chain tensioner)
Typical mileage:
80000-140000 miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
BrakesMedium severity📝 Editorial
The motors of the rear electric handbrake on the 2003 to 2010 A8 were described as prone to failing, at a cost of at least £600 for each side, and aftermarket warranty firms were said to be reconsidering whether to cover them.
Rough guide
£600
Typical symptoms
Handbrake warning light on
Electric handbrake slow or failing to apply or release
Affected vehicles
Engines:
All engines
Typical mileage:
unknown miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
What owners report
10 single reports, unconfirmed
One owner each, in their own words rewritten as a line, and not counted in our risk scoring. A fault joins the list above once a second report or an editorial source backs it.
Fuel system · September 2018A 2012 A8 3.0 V6 diesel suffered a failure of its high-pressure fuel pump, leading to an estimated £10,000 repair cost.
Gearbox and clutch · April 2018A 2010 A8 3.0 V6 TDI experienced a 'Mechatronics' failure in its 8-speed torque converter transmission at 60,000 miles.
Bodywork · January 2017A 2015 A8 3.0 V6 TDI LWB had repaired body damage, intermittently thumping rear suspension, failing brakes, and an AdBlue leak.
Engine · October 2016A 3.0 V6 TDI A8 experienced carbon build-up affecting the inlet manifold swirl flaps, requiring replacement of multiple components.
Engine · June 2016A 2008 A8 3.0 TDI with 145,000 km developed a coolant leak from multiple sources, including cylinder gaskets, and extensive carbon deposition.
Electrics · July 2015Smoke appeared from under the bonnet of a 2005 A8 W12 at 75,000 miles, caused by a major electrical short circuit with heat damage.
Electrics · February 2014A 2011 A8 SE TDI Quattro Auto with 75,000 miles lost all power due to a corroded automatic transmission wiring loom.
Engine · October 2013An April 2012 A8 4.2 experienced engine surge and vibration, with diagnostic codes indicating camshaft position sender and air system faults.
Bodywork · December 2012A leak was reported from the overhead lights console, dripping onto the gearshift, alongside issues with headlight intensity and misting.
Electrics · April 2011A four-year-old A8 required replacement of its compressor, intake manifold, door handles, aerial booster, and mirror motors.
What owners like
4 notes
December 2013A 3.0 TDI quattro SE version of the A8 L was named the best chauffeur vehicle at the 2013 Professional Driver Awards.
June 2009Audi received the 4th overall Manufacturer Award in the British Insurance Vehicle Security Awards for its range's security.
The A8 range was awarded an ABI 'Best in Class' Security rating, highlighting its strong protective features.
The A8 was recognised as 'Britain's Most Secure Car' in the 2005 Thatcham tests, demonstrating its robust security.
Other years0 known faults · 3 good notes
Other Audi A8 years: owner reports
What owners like
3 notes
The A8 offers an effortless driving experience, making it easy and enjoyable to operate on various journeys.
The A8 features a large and luxurious interior, providing ample space and comfort for occupants.
The A8 is equipped with innovative technology, offering advanced features and systems for enhanced convenience and safety.
Sellers rarely admit these faults outright
We track 7 specific phrases sellers use in adverts to soft-pedal these exact issues. Paste any Audi A8 advert and we check it in seconds.
An overdue cambelt is the most expensive thing a seller can fail to mention on a used A8. These are the figures UK specialists work to.
Timing belt (cambelt)Belt
2.5 V6 TDI, 2.5 TDI
60,000 miles or 4 years, whichever comes first
Notorious engine. Audi's schedule said 80,000 miles with a check at 40,000 and no time limit, but the 2.5 V6 TDI's reputation for camshaft and rocker wear (pre-2003 AFB/AKN especially) and belt-drive failures means UK garage advice is 60,000 miles and 4-5 years; the shorter 60,000 miles / 4 years is recorded. Interference engine and failure is usually terminal.
Always confirm against the vehicle handbook. Intervals vary by engine, and several manufacturers revised theirs after failures in service.
Repair costs are typical UK ranges, not quotes. Actual cost depends on condition and garage.Data last verified: November 2026
Audi A8 buying questions
What are the most common Audi A8 problems?
Three stand out. Engine: timing chain tensioner failure causing severe rattling (typically 80000 to 140000 miles). Gearbox: the first-generation A8 was said to have had a run of failures involving the electronic control. Brakes: the motors of the rear electric handbrake on the 2003 to 2010 A8 were described as prone. The full list above is grouped by generation, with typical mileage and a rough repair cost for each.
Which Audi A8 years should I avoid?
No Audi A8 year is a write-off, but the Audi A8 (2003 to 2010) carries the most serious faults: engine. The Audi A8 (1994 to 2003) has high-severity faults on record too. Year matters less than whether the specific car has had the known fixes, so check the history for them.
What should I check when viewing a used Audi A8?
Ask the seller about the engine, gearbox and brakes faults on this page and whether they have been fixed, with invoices. On the test drive watch for loud metallic slapping/rattling from the back of the engine on cold start, automatic gearbox failing to change gear properly and handbrake warning light on. Read the MOT history for repeat advisories, then paste the advert into the free check, which reads it against all 3 known faults before you travel. Check a Audi A8 advert →
What is the real MPG of an Audi A8?
Owners report 35.3 mpg on average across the Audi A8 engines with data, about 94% of the official combined figure. The gap between official and real-world economy varies a lot by engine, so the Real MPG page lists every engine and generation separately, from 232 owner submissions. Audi A8 Real MPG by engine →
If you used to check the Honest John “Good & Bad” section before the site closed in 2026, this page is where that information now lives. We rebuilt the Audi A8 owner-report history from the archived Honest John dataset, added our own research, specialist and owner-club sources and DVSA recall data, and we keep it free. Each fault above is badged with its source. The same data feeds our free advert check, which reads a listing against every known fault for the exact engine and year.