Audi2011–2023 Critical issues documented

Audi S6 C8: common faults & what to check

The C8 is the Audi S6 built 2019 onward. Of the 9 faults documented for the S6, 4 apply to this generation, each with its symptoms, what to inspect and a typical repair cost. Free, no account needed.

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Documented faults

Critical

Most serious

$1,600–$5,500

Typical repair

Service milestones

You're looking at the C8

Everything below is narrowed to this variant. Pick a different one to change it.

2019–nowC8 Selected2019–nowC8Engine not documented for this generationEngine not documentedDocumented issues4 knownSee faults & what to checkPhoto: Alexander Migl via Wikimedia Commons, CC BY-SA 4.0.

Choose a different generation

Now narrow it to the engine

A 1.8 and a 2.4 of the same car do not fail the same way, so the faults below narrow to the engine as well as the year. Free, no account needed.

A 2020 Audi S6 is the C8 generation (2019 to now).

Start your free check on this Audi S6

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Audi S6 C8

Can't confirm for this car

Audi S6 · 2020

Narrowed to the year. No engine is recorded for this vehicle. Pick an engine to see which faults apply.

Tell us the engine, or check the engine code on the car, before relying on this.

No engine is recorded for this vehicle.

matched on year only

What to look out for

The checks worth doing on a Audi S6 before you hand over any money. Every documented fault is listed below, each with its own page.

Costly issue
Inspect the vehicle after it has sat overnight — check all four corners are at equal, correct ride height.
See why
Adaptive Air Suspension Compressor and Height Sensor Failure
The optional (and fitted as standard on many A6 variants sold in NZ/AU) Audi air suspension uses an electric compressor to maintain air spring pressure and four height sensors to communicate ride height to the control module. The compressor motor brushes wear out and the compressor membrane cracks, while the potentiometric height sensors corrode at their pivot points or suffer wiring harness chafing near the wheel arch. Both faults trigger the suspension warning light and can cause the vehicle to sit noticeably low on one or more corners overnight. Continued driving on a failed compressor accelerates air strut wear.
What you would notice
- Suspension warning light and message 'Suspension fault: do not exceed 80 km/h'
- Vehicle sitting visibly lower on one corner or all corners after an overnight park
- Audible compressor running continuously or for long periods after start-up
- Uneven or bouncy ride quality on one axle compared to the other
- Fault codes for height sensor implausible signal stored in the suspension control module
Typically $900–$4,500 to put right.

Audi S6 service schedule

The 2 engines a 2020 Audi S6 was sold with, each with its own intervals. Pick your engine above to narrow this to one. These are the model’s intervals — the car’s own service book is the only thing that can tell you what has actually been done to it.

Audi S6 C8 · 2019–2026 · 3.0L TDI V6 Turbo - Quattro Sedan/Avant (European/NZ Market)

Diesel

Due by distance

60,000 km
First major service interval; transmission fluid and differential oils should be inspected for long-term drivetrain longevity.
100,000 km
Engine mounts and suspension air bags may show wear here, depending on the road surfaces travelled.
120,000 km
Cooling system components, such as the water pump and thermostat housing, may warrant a proactive check to maintain optimal engine temperature.

Audi S6 C8 · 2019–2026 · 2.9L TFSI V6 Twin-Turbo - Quattro Sedan/Avant

Petrol

Due by distance

60,000 km
Transmission fluid and filter service maintains smooth power delivery.
90,000 km
Review the brake discs and pads, especially given the S6's performance capabilities.
120,000 km
Have a specialist inspect the cooling system hoses and auxiliary water pump as a proactive measure for long-term reliability.

See all 4 issues for this oneDocumented for the exact year and engine you picked.

Body, brakes, suspension & interior1

01Adaptive Air Suspension Compressor and Height Sensor Failure

Inspect the vehicle after it has sat overnight — check all four corners are at equal, correct ride height.2011–2023Suspension$900–$4,500

CommonSuspension $900–$4,500 to fix

The optional (and fitted as standard on many A6 variants sold in NZ/AU) Audi air suspension uses an electric compressor to maintain air spring pressure and four height sensors to communicate ride height to the control module. The compressor motor brushes wear out and the compressor membrane cracks, while the potentiometric height sensors corrode at their pivot points or suffer wiring harness chafing near the wheel arch. Both faults trigger the suspension warning light and can cause the vehicle to sit noticeably low on one or more corners overnight. Continued driving on a failed compressor accelerates air strut wear.

Symptoms to notice

Suspension warning light and message 'Suspension fault: do not exceed 80 km/h'
Vehicle sitting visibly lower on one corner or all corners after an overnight park
Audible compressor running continuously or for long periods after start-up
Uneven or bouncy ride quality on one axle compared to the other
Fault codes for height sensor implausible signal stored in the suspension control module

What to check

Inspect the vehicle after it has sat overnight — check all four corners are at equal, correct ride height.
Start the engine and listen for the compressor running for an extended period (more than 30 seconds) to maintain pressure, indicating a leak.
Check the height sensor linkage rods at all four corners for corrosion or play.
Scan for fault codes C10B3, C10B7 (height sensors) and C0795 (compressor circuit).
Check the compressor reservoir under the rear floor for moisture contamination.

Where to look: Compressor located in the spare wheel well or boot floor; height sensors at each wheel knuckle with a linkage rod to the control arm

Parts involved: Air suspension strut.

Ask the seller

“Has the air suspension compressor or any of the height sensors been replaced, and does the system hold ride height overnight?”
“Has the suspension warning light ever appeared, and has any suspension fault been diagnosed or cleared?”

Depends on the exact engine — 3 moreDocumented for a specific engine we could not confirm from what you picked. Check the engine code on the car.

Engine, transmission & cooling3

013.0 TFSI DKNA Timing Chain Tensioner Wear

Cold-start the vehicle from overnight-cold and listen for chain rattle from the top of the engine in the first 10 seconds.petrol2018 onwardEngineCan't confirm for this car$3,500–$12,000

OccasionalEngine $3,500–$12,000 to fix

Can't confirm for this car

The EA839 3.0 TFSI V6 (DKNA) in the C8 A6 uses hydraulic chain tensioners and plastic guide rails on both camshaft drive banks. Under extended oil service intervals or low oil pressure at start-up, the tensioners lose pre-load and the chains develop elongation on one or both banks. The condition presents as a brief cold-start rattle that clears within seconds as oil pressure builds. If ignored the chains can develop enough slack to cause camshaft timing variance on both banks independently. Early intervention limits repair to tensioner and guide rail replacement; delayed repair risks camshaft and valve damage on a fresh-generation engine.

Symptoms to notice

Brief cold-start chain rattle from engine top-end clearing within 5-10 seconds
Camshaft timing correlation fault codes on one or both banks in P0016 group
Slightly rough cold idle that smooths at operating temperature
Check engine light appearing after extended cold-start drives
Increased oil consumption noted alongside chain noise in advanced cases

What to check

Cold-start the vehicle from overnight-cold and listen for chain rattle from the top of the engine in the first 10 seconds.
Scan for camshaft correlation fault codes on both banks.
Review oil service history — the DKNA requires 0W-20 long-life specification oil changed no later than every 15,000 km under Australasian conditions.
Inspect for seepage around the timing cover.

Where to look: Both camshaft chain banks at front of EA839 V6 engine behind the front plastic timing cover

Parts involved: Timing chain.

Ask the seller

“What oil grade and brand has been used and has the correct 0W-20 specification always been followed?”
“Has any cold-start chain rattle been noticed or any timing-related fault codes appeared?”
“Have the timing chain tensioners or guide rails ever been replaced or inspected by Audi?”
“Does the dealer or specialist have a record of any camshaft bank correlation fault codes?”

02AdBlue SCR System NOx Sensor and Injector Failure (Post-Euro 6 3.0 TDI)

Scan for P20EE (SCR catalyst efficiency below threshold), P2201/P2202 (NOx sensor), and P204F (reductant system performance) codes.diesel2015–2023EngineCan't confirm for this car$600–$9,000

OccasionalEngine $600–$9,000 to fix

Can't confirm for this car

Euro 6 compliant 3.0 TDI variants (CKVB and later) use a selective catalytic reduction (SCR) system with AdBlue injection to reduce NOx emissions. The NOx sensor upstream and downstream of the SCR catalyst, as well as the AdBlue dosing injector and its heating element, are documented failure points. A failed NOx sensor or blocked injector triggers an escalating warning system: after a set number of engine starts the car enters a performance-limited mode, and eventually will not start until the fault is repaired and reset by a dealer. AdBlue injector nozzle carbonising is particularly common in low-mileage city-use vehicles.

Symptoms to notice

Warning message 'AdBlue: Have system checked by a workshop' with a countdown of permitted engine starts
Reduced engine power or refusal to start after the fault countdown expires
P20EE, P2201, or P204F fault codes on diagnostic scan
White crystalline residue around the AdBlue filler cap or tank area indicating past leakage
Engine running rough or slightly rich under load if the NOx sensor is providing incorrect feedback

What to check

Scan for P20EE (SCR catalyst efficiency below threshold), P2201/P2202 (NOx sensor), and P204F (reductant system performance) codes.
Check the AdBlue tank level and inspect the filler neck for crystallised AdBlue (white powdery residue indicating past overfill or contamination).
Ask the seller when the AdBlue was last topped up and whether genuine AdBlue meeting ISO 22241 specification was used — contamination with water or wrong fluid kills the injector and catalyst.

Where to look: NOx sensors on the exhaust system downstream of the diesel particulate filter; AdBlue injector on the exhaust pipe ahead of the SCR catalyst, typically near the rear axle

Parts involved: Fuel injector.

Ask the seller

“Has any AdBlue or SCR system warning light appeared, and has the car ever entered a reduced-start countdown mode?”
“Can you confirm what brand and specification of AdBlue has been used, and whether the system has ever been diagnosed for NOx or catalyst faults?”

032.0 TFSI and 3.0 TFSI Intake Valve Carbon Deposit Buildup

Ask for service records showing when (if ever) the intake valves were walnut blasted.petrol2011–2023EngineCan't confirm for this car$900–$2,000

CommonEngine $900–$2,000 to fix

Can't confirm for this car

All TFSI petrol engines in the A6 use gasoline direct injection (GDI), where fuel is sprayed directly into the combustion chamber rather than the intake port. This means fuel never washes the intake valves, and oil vapor from the positive crankcase ventilation (PCV) system coats the valve stems and backs with hard carbon deposits over time. By 60,000-100,000 km the deposits restrict airflow enough to cause rough idle, misfires, and reduced power. The only effective remedy is walnut shell blasting of the intake ports, which requires intake manifold removal.

Symptoms to notice

Rough idle that is most pronounced when the engine is cold and improves as it warms up
Hesitation and stumble during light throttle acceleration in lower RPM range
Slightly reduced power and fuel economy compared to a known good example
Occasional misfires logged as P030X codes without any ignition or injector fault found
Carbon deposits visible through the intake ports on borescope inspection

What to check

Ask for service records showing when (if ever) the intake valves were walnut blasted. Vehicles using the PCV system that has been serviced regularly show slower buildup. Request a borescope inspection of the intake valves through the intake ports after removing the air cleaner assembly — heavy deposits appear as grey/black walnut-shell-shaped buildup around the valve head. If a workshop inspection is possible: Compare cylinder balance data from a scan tool; imbalanced cylinders often indicate restricted valves.

Where to look: Intake valves inside the cylinder head, accessible via the intake ports after manifold removal

Parts involved: PCV / oil separator, Intake manifold.

Ask the seller

“Have the intake valves ever been walnut blasted or carbon cleaned, and at what mileage?”
“Has the car ever exhibited a rough idle or hesitation at light throttle that was attributed to the engine?”

Other Audi S6 engines and years5 documented issues that do not apply to the one you picked.

Engine, transmission & cooling2

013.0 TDI B-bank Timing Chain Tensioner and Sprocket Failure

Cold-start the engine and listen for chain rattle from the front/right of the engine in the first 5-10 seconds before oil pressure builds.diesel2011–2019EngineDoes not apply$3,500–$22,000

CommonEngine $3,500–$22,000 to fix

Does not apply

The B-bank (right cylinder bank) timing chain tensioner loses hydraulic pressure or the plastic chain guide wears through on the CDUD and CKVB 3.0 TDI V6. The chain can jump teeth or snap, bending valves and causing catastrophic engine damage. The failure occurs without warning and is more pronounced on high-mileage examples that have not had regular oil changes with specified low-SAPS oil. Audi issued a TSB and extended warranty in some markets but this is not universally covered.

Symptoms to notice

Rattling or chattering noise from the right front of the engine on cold start that fades as oil pressure builds
Engine management warning light with P0016, P0017, P0018 or P0019 camshaft correlation codes
Rough running or misfires after the chain jumps teeth
Sudden complete engine failure if the chain snaps
Oil consumption above 0.5 L per 1,000 km as an early indicator of wear

What to check

Cold-start the engine and listen for chain rattle from the front/right of the engine in the first 5-10 seconds before oil pressure builds.
Pull oil filler cap and inspect for metal swarf.
Request full service history showing correct oil specification (VW 507.00).
Check for any Audi extended warranty or goodwill repair history on this specific fault.

Where to look: Right (B-bank) side of the V6 engine, front timing cover area

Parts involved: Timing chain.

Ask the seller

“Has the timing chain ever been inspected or replaced, and do you have documentation of oil changes using VW 507.00 specification oil?”
“Has the car ever shown a cold-start rattle or any camshaft correlation fault codes, even if cleared?”

02S-Tronic DL501 Mechatronic Unit Failure

Test all gear positions including reverse for smooth engagement.2011–2018TransmissionDoes not apply$3,500–$7,500

CommonTransmission $3,500–$7,500 to fix

Does not apply

The 7-speed DL501 S-Tronic dual-clutch gearbox fitted to A6 C7 models houses its shift solenoids, clutch pressure control valves, and electronic control module in a single mechatronic unit submerged in transmission fluid. Heat from the wet clutch pack and electrical cycling degrade the unit's circuit board solder joints and solenoid windings. Solenoid failure disrupts clutch pressure and gear-selector regulation, producing erratic shifts, limp mode, or a complete inability to select gears. The integrated design means the entire mechatronic unit must be replaced or rebuilt rather than repairing individual components.

Symptoms to notice

Harsh, jerky, or delayed gear changes — particularly 2nd to 3rd and 4th to 5th
Gearbox warning light and PRNDS indicator flashing on the dashboard
Transmission entering limp mode and refusing to shift above first or second gear
Loss of reverse or inability to select drive after starting the engine

What to check

Test all gear positions including reverse for smooth engagement.
Ask for any transmission service history including fluid and filter changes.
If a workshop inspection is possible: Connect a diagnostic tool capable of reading transmission-specific codes and check for P17D8 (clutch torque limitation), P176A through P176D (gear selector regulation faults), and P17D6 or P17D7 (clutch pressure faults) — these confirm mechatronic failure.

Where to look: Inside the S-Tronic gearbox casing, accessible after partial gearbox removal

Parts involved: Mechatronic / valve body.

Ask the seller

“Has the S-Tronic mechatronic unit been replaced or rebuilt?”
“Any history of harsh shifts, limp mode, or a gearbox warning light?”
“Is there a record of transmission fluid and filter service?”

Body, brakes, suspension & interior3

01Air Suspension Front Strut Air Bladder Failure

Park on a level surface overnight and check front ride height in the morning before starting.2011–2018SuspensionDoes not apply$1,600–$5,500

CommonSuspension $1,600–$5,500 to fix

Does not apply

The C7 A6 Adaptive Air Suspension uses rubber air bladder bellows on each front strut. The front bladders are prone to cracking at the convolute folds due to rubber degradation from UV exposure, ozone, and repeated compression cycles over time. A cracked bladder causes a slow or rapid air leak, dropping the front ride height — typically most visible after the vehicle has sat overnight. The air compressor attempts to compensate by running excessively, eventually burning out the compressor motor if the leak is not repaired. Replacement with genuine Audi bladders is required for lasting reliability; budget aftermarket units carry high re-failure rates in Australasian UV conditions.

Symptoms to notice

Front of vehicle sitting noticeably lower than rear, especially after overnight parking
Air suspension warning or chassis fault message on MMI display
Compressor cycling audibly when vehicle is parked or at idle
Uneven front ride height left-to-right
Vehicle drops to bumpstops on cold mornings with advanced bladder failure

What to check

Park on a level surface overnight and check front ride height in the morning before starting.
Listen for compressor running when the car is parked.
Spray soapy water around the base of each front strut and along the rubber bellows convolutes to identify air bubbles indicating leaks.
Scan suspension module fault codes via VCDS.
Confirm compressor run time has not been excessive — a damaged compressor from a long-running bladder leak adds $800-$1,800 to repair cost.

Where to look: Front left and front right air strut assemblies — rubber bellows section visible mid-strut behind wheel arch liner

Parts involved: Air suspension strut, Shock absorber / strut.

Ask the seller

“Has the air suspension ever dropped, triggered a fault light, or been repaired for leaks?”
“Have any front or rear air struts or the air compressor been replaced?”
“Does the car sit level front and rear when you come back to it after leaving overnight?”
“Has the vehicle ever been driven on failed or collapsed air suspension?”

02Air Suspension Strut Perishing and Compressor Failure (C7)

Inspect ride height at all four corners for consistency.petrol2011–2018SuspensionDoes not apply$1,200–$5,500

CommonSuspension $1,200–$5,500 to fix

Does not apply

The C7 A6 equipped with air suspension (standard on some Quattro variants and optional on others) uses air struts with rubber air bags that perish with age. Cracked air bags cause one or more corners to sag. The compressor runs continuously to compensate, overheating and burning out. Both front and rear struts fail; rear struts are the most common failure point on C7 examples in NZ. Given the age of C7 imports now entering the NZ used market, this fault is increasingly common and is frequently undisclosed by private sellers.

Symptoms to notice

Car sitting noticeably lower at one or more corners when parked
Air suspension or chassis fault warning on the Audi MMI cluster
Compressor audible running continuously from the boot area
Hissing noise from a wheel arch, particularly at the rear

What to check

Inspect ride height at all four corners for consistency.
Listen near each wheel arch with the engine off for air leaks.
Scan the suspension control module for fault codes including compressor overtemperature.
Confirm whether the car raises and lowers correctly across all height settings.
Ask how long the fault has been present.

Where to look: Air struts at each corner; air suspension compressor in the rear of the boot or spare wheel well

Parts involved: Air suspension strut, Shock absorber / strut.

Ask the seller

“Does the car sit level at all four corners at all times, including after sitting overnight?”
“Has any air strut or the compressor been replaced?”
“Any suspension warning lights active or recorded in history?”

03C7 Front Lower Control Arm Ball Joint and Bush Failure

Repeat at 12 and 6 o'clock positions to check wheel bearing and strut top mount.2011–2018SuspensionDoes not apply$1,600–$4,000

CommonSuspension $1,600–$4,000 to fix

Does not apply

The C7-generation A6 uses a multi-link front suspension with aluminium lower wishbones. The pressed-in rubber bushings at the front and rear of the lower control arm deteriorate from age and road grime, causing clunking over bumps and vague steering response. More critically, the lower ball joint (either integral to the arm or a separate pressed-in unit depending on the variant) wears through its housing, producing a knocking sound under braking and cornering. A failed ball joint is a loss-of-control risk. Audi specifies replacement of the complete arm rather than bush-only or ball-joint-only repair on most configurations.

Symptoms to notice

Clunking or knocking sound from the front suspension when driving over speed bumps, pot holes, or rough road joins
Steering wander or vagueness on straight roads, requiring constant small corrections
Steering wheel pulling to one side under braking on a smooth road
Visible cracking or deformation of the rubber bush boots on the lower control arm
Premature or uneven front tyre wear across the tread width

What to check

Repeat at 12 and 6 o'clock positions to check wheel bearing and strut top mount. Inspect the lower control arm bushings for cracking or collapse — the rear bush in particular tends to split. On a test drive, listen for clunking over road joins and check for steering wander on straight roads. If a workshop inspection is possible: With the vehicle on a hoist, grasp each front wheel at 9 and 3 o'clock and attempt to rock it — any clunk or detectable movement at the ball joint is a failure.

Where to look: Front lower control arm (wishbone) on both sides, particularly the rear bush and outboard ball joint

Parts involved: Ball joint.

Ask the seller

“Has the front suspension been inspected recently, and have any control arms, ball joints, or bushings been replaced?”
“Has the car passed its most recent WOF inspection with no suspension advisories, and does the steering feel tight and responsive?”

What these repairs cost on other cars

Some of the Audi S6’s documented faults are repairs other models share. Each page lists the documented NZ cost for every model it affects.

Other Audi models

Audi A445 documented faults Audi A343 documented faults Audi A634 documented faults Audi A87 documented faults Audi RS47 documented faults Audi A76 documented faults

Audi S6 buyer questions

Is the Audi S6 reliable?

Like any used car, it depends on the specific example and its service history. Across the 9 documented faults for the Audi S6, the recurring problem areas are engine, transmission, and suspension. A Audi S6 with a full service history and no signs of the issues listed on this page can be a sound buy but each one needs to be checked individually before you commit.

What are the most common problems with a used Audi S6?

We've catalogued 9 known faults for the Audi S6, covering engine, transmission, and suspension. All 9 are written out in full on this page, with the symptoms to notice, what to inspect, and typical repair costs for each. Free to read, no account needed.

How much do repairs cost on a Audi S6?

Most single repairs on the Audi S6 fall between $1,600–$5,500 at NZ independent-workshop rates. Some of the 9 documented faults cost less and a few cost considerably more, and no one car needs them all. Knowing which ones to look for before you view is what lets you negotiate the price down or walk away.

Should I get a pre-purchase inspection on a Audi S6?

Yes. A Audi S6 inspection focused on its known weak points is the single best way to avoid an expensive mistake. KickTyres gives you a guided, model-specific inspection plus a market valuation and negotiation figure for $24.90 far less than the cost of missing one of the faults on this page.