Executive refinement, choose your engine wisely
The A6 is Audi's executive saloon/estate, competing directly with the BMW 5 Series and Mercedes E-Class. The C7 generation (2011-2018) is the current used market sweet spot, offering genuine luxury at £10,000-£20,000. The C8 (2018+) starts from £22,000-£40,000 used. All A6s are well-equipped with Quattro AWD available across the range. However, complexity means higher maintenance costs than mainstream cars, and the A6 ranks mid-table in executive car reliability surveys.
We track 14 known issues across the Audi A6 range, including 3 rated as safety-critical. Knowing which variants and configurations to approach with caution can save you from expensive surprises after purchase.
Found a Audi A6? Enter the reg to see which of our 14 known issues apply to that exact car, plus full MOT history and mileage checks.
C5 (1997–2004) — Petrol options included the 1.8T 20V, 2.4 V6, 2.8 V6, 4.2 V8, with 1.9 TDI, 2.5 TDI V6, 2.7T Biturbo on the diesel side. We track 3 known issues on this generation, with 1 classified as significant. The most significant concern is Turbocharger failure (£1,500–£3,000 to address).
C6 (2004–2011) — Petrol options included the 2.0 TFSI, 2.8 FSI V6, 3.2 FSI V6, 4.2 FSI V8, 5.2 FSI V10, with 2.0 TDI, 2.7 TDI V6, 3.0 TDI V6 on the diesel side. Our database flags 7 known issues on this generation, 3 of which are rated as safety-critical. The most significant concern is Oil pump drive failure (£1,500–£3,000 to address).
C7 (2011–2018) — Petrol options included the 1.8 TFSI, 2.0 TFSI, 3.0 TFSI Supercharged, 4.0 TFSI V8, with 2.0 TDI, 3.0 TDI V6 on the diesel side. We track 6 known issues on this generation, with 5 classified as significant. The most significant concern is High oil consumption and timing chain (£500–£2,000 to address).
C8 (2018–2024) — Petrol options included the 2.0 TFSI, 3.0 TFSI V6, 4.0 TFSI V8, with 2.0 TDI, 3.0 TDI V6 on the diesel side. We track 2 known issues on this generation, with 1 classified as significant. The most significant concern is Starter alternator failure (mild hybrid) (£500–£1,200 to address).
The oil pump drive on PD TDI engines is secured by a single hex bolt that can shear without warning, causing immediate loss of oil pressure and catastrophic engine failure. This is the same design flaw that affects the B7 A4 and represents one of the most serious failure modes on these engines. The failure typically occurs without any prior symptoms, making it impossible to predict. Updated bolt kits are available but require engine removal to fit.
If the hex bolt shears, the oil pump stops immediately, causing complete loss of lubrication and engine seizure within seconds. Engine rebuild costs typically exceed £4,000-£8,000. The car becomes immediately undriveable and unsafe.
Check the oil level before the engine is started. Ask the seller how often they top up the oil between services. After a test drive, check the level again and look behind the car for blue or grey exhaust smoke under acceleration.
The intake manifold swirl flaps on V6 TDI engines can break and fall into the cylinders, causing catastrophic internal engine damage. These plastic flaps are designed to improve airflow at low RPM but the mounting screws can work loose or the plastic can become brittle. Once a flap enters the combustion chamber, it typically destroys pistons, valves, and cylinder head components. Many owners have the flaps removed preventively.
If swirl flaps break and enter the cylinders, repair costs typically exceed £5,000-£8,000 for cylinder head rebuild or replacement. The engine may need complete reconstruction. Many specialists recommend preventive removal of the flap mechanism.
Check for any engine warning lights on the dashboard. Ask about the car's MOT emissions history — repeated failures suggest underlying issues. A pre-purchase diagnostic scan is especially worthwhile to check for stored emissions fault codes.
The EA888 generation 1 engine suffers from two critical failures: timing chain tensioner wear causing chain stretch and jump, and high-pressure fuel pump cam follower wear that can destroy the camshaft. Both issues can cause catastrophic engine damage and often occur together. The timing chain tensioner uses a plastic guide that wears prematurely, while the HPFP cam follower wears the camshaft lobe. These are among the most serious known faults on this engine generation.
Timing chain failure can cause valve and piston damage requiring engine rebuild. Cam follower failure destroys the camshaft requiring cylinder head removal. Combined repair costs typically exceed £3,000-£6,000. The engine may suffer catastrophic failure if driven with these faults.
Listen carefully for a rattle or ticking noise from the engine on cold start — this is the most common early sign. Ask for evidence of chain replacement in the service history. On higher-mileage cars without documented replacement, budget for preventative work.
The 2.7T Biturbo uses twin K03 turbochargers that are prone to bearing failure, particularly the turbine-side bearings. Oil starvation from blocked oil feed lines or poor maintenance accelerates failure. When one turbo fails, the other typically follows due to increased load and debris contamination through the intercooler system. Replacement costs are high due to the twin-turbo configuration and the need to replace both units simultaneously.
Failed turbochargers cause significant power loss and poor fuel economy. Oil contamination from failed seals can damage other engine components. Twin turbo replacement typically costs £2,000-£4,000 plus labor. The car remains driveable but with severely reduced performance.
During a test drive, check for hesitation, lack of power or unusual whining from the turbo area. Watch for blue or white smoke from the exhaust under hard acceleration. Check the oil condition and service history — turbos rely on clean oil.
The diesel particulate filter on V6 TDI engines becomes clogged when the car is used primarily for short journeys that don't allow the DPF to reach regeneration temperature. The system requires extended highway driving to burn off accumulated soot particles. Cars used mainly in urban environments suffer premature DPF failure, triggering warning lights and limp mode. Replacement DPF units are expensive and the problem will recur unless driving patterns change.
Severely clogged DPF causes limp mode, reduced power, and eventually prevents the engine from starting. Professional cleaning costs £300-£600, while DPF replacement costs £1,500-£2,500. The problem will recur unless driving patterns include regular longer journeys.
Ask about the car's typical usage — short urban journeys prevent DPF regeneration. Check for DPF warning lights and ask about any previous regeneration issues. A forced regeneration at a garage costs far less than a DPF replacement.
For the full breakdown of all 14 tracked issues with repair costs, see the Audi A6 common problems page.
Based on 723k real DVSA MOT tests, the Audi A6 fails more often than average on several items. The biggest outlier is coil springs broken at 71x the fleet average, followed by any fracture or welding defect on a wheel (35x).
When viewing a specific car, check its MOT history for recurring advisories in these categories. See the full Audi A6 MOT failure breakdown for data at every mileage point.
Routine servicing (oil and filter change every 10k miles) typically costs £80–£150 at an independent garage.
The bigger-ticket items to budget for include timing belt (£400–£600), timing chain service (£800–£1,500), automatic transmission fluid (£250–£400).
See the full Audi A6 service schedule for every interval and cost breakdown.
The Audi A6 has some well-documented weak points, including 3 safety-critical issues that demand careful checking. The right example, properly maintained, can still be a sound purchase — but cutting corners on the pre-purchase inspection is not advisable. 2014-2017 C7 facelift (C7.5) with the 3.0 TDI V6 Quattro and 8-speed torque converter automatic. This avoids the C6's catastrophic chain failures, gets the improved tensioner, and uses the robust ZF 8-speed rather than the S-tronic DSG. For budget buyers, 2015-2016 C7.5 2.0 TDI Ultra (FWD, manual) is frugal at 60+ mpg and avoids both the Multitronic and S-tronic gearboxes.
Before committing, check the car's full MOT history, verify the service record is complete, and if possible arrange a specialist inspection. Enter any registration into our free report to see the complete picture.
Get Car Wise maintains a database of known mechanical issues for every popular car on UK roads, tracking the faults that owners, specialists and DVSA data reveal.
When you run a report on a specific Audi A6, we cross-reference the exact variant, engine and age against our database of 14 known issues. Combined with full MOT history analysis, mileage verification and DVLA data, you get a complete picture before viewing.
Enter the registration for MOT history, mileage verification, known faults for that exact variant, and a Get Car Wise Score.
This guide was compiled from independent expert reviews, DVSA MOT data, specialist workshops and our own database of 14 known Audi A6 issues. We are not affiliated with any source listed.