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Audi1997–2023 Critical issues documented

Audi A6 C8: common faults & what to check

The C8 is the Audi A6 built 2019 onward. It was sold here with the 2.0 TFSI mild-hybrid and 3.0 TFSI. Of the 34 faults documented for the A6, 7 apply to this generation, each with its symptoms, what to inspect and a typical repair cost. Free, no account needed.

Check this exact Audi A6

  • Odometer history
  • Money owing
  • Reported stolen
  • Ownership history
  • Official NZ vehicle register data
  • NZ owned and operated

Type the plate for the free basics. The full record is a paid check from $13.49, one car at a time, no subscription.

No NZ plate yet, or buying in Australia? Pick the generation and engine and start a free check below. New to KickTyres? How the check works →

34

Documented faults

Critical

Most serious

$1,200–$4,500

Typical repair

72

Service milestones

You're looking at the C8

2 engine variants are documented for this generation. Pick yours to narrow further, or keep reading for the generation as a whole.

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 A6 is the C8 generation (2019 to now).

Start your free check on this Audi A6

No plate needed. You get the risk score, the buyer's checklist and the guided inspection for the exact car you picked above — not the whole nameplate.

Audi A6 C8Engine not picked yet

Pick the engine above first: the A6 came with 2, and without it the report has to show all of their faults. Pick the engine

Free. The paid plate check is separate, and stays optional.

Can't confirm for this car

Audi A6 · 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 A6 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.

  • Worth checking

    In traffic let the engine stop-start several times and note whether restarts are smooth.

    See why

    48V mild-hybrid / start-stop faults and rough restarts

    The C8 A6 uses a 48-volt mild-hybrid system with a belt-driven starter-generator that handles the frequent engine stop-start and coasting. Owners report harsh or slow engine restarts, start-stop dropping out, and occasional 12V/48V electrical warnings, sometimes traced to the auxiliary battery or the starter-generator. It rarely leaves you stranded but can be an expensive out-of-warranty diagnosis.

    What you would notice

    • Harsh or delayed engine restart from stop-start
    • Start-stop stops working
    • Electrical/battery warning messages
    • Jerky low-speed coasting-to-restart

    Typically $600–$3,000 to put right.

  • Worth checking

    Sit in the car and work through both screens - reversing camera, phone pairing, climate, and let it sit to see if anything reboots.

    See why

    MMI dual-touchscreen software glitches and blank screens

    The C8 A6's twin-touchscreen MMI can freeze, reboot, or go black, and features such as reversing camera, phone connection or climate control (which lives in the lower screen) can drop out until a restart or software update. It is usually a software/module issue rather than a wiring fault, but a persistently faulty screen is costly out of warranty because so many functions depend on it.

    What you would notice

    • Screen freezes, reboots or goes black
    • Reversing camera or CarPlay dropping out
    • Climate/haptic controls unresponsive
    • Random warning chimes

    Typically $0–$2,500 to put right.

Audi A6 service schedule

The 5 engines a 2020 Audi A6 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.

C8 · 2020–2024 · 55 TFSI e Plug-in Hybrid - Quattro

Hybrid

Due by distance

  1. 60,000 km

    Comprehensive transmission fluid service and thorough inspection of the hybrid battery cooling system.

  2. 90,000 km

    Inspect suspension bushings and consider replacing secondary cooling system components.

  3. 120,000 km

    Major service interval: review the high-voltage cable connectors and ancillary drive belts.

C8 · 2019–2021 · 40 TDI 2.0L - FWD

Diesel

Due by distance

  1. 60,000 km

    First significant service interval for the S-tronic transmission fluid and filter change.

  2. 90,000 km

    Monitor the condition of the brake discs and pads, depending on driving style.

  3. 120,000 km

    Proactive inspection of suspension components and engine mounts, recommended to maintain the Audi-standard ride quality.

C8 · 2019–2023 · 45 TFSI 2.0L - FWD

Petrol

Due by distance

  1. 60,000 km

    First major transmission fluid and filter service, keeping the S-tronic shifting perfectly.

  2. 90,000 km

    Inspect the cooling system hoses and auxiliary water pump for seepage.

  3. 120,000 km

    Thorough check of the engine mounts and suspension bushings, to maintain that signature Audi comfort.

C8 · 2019–2024 · 50 TDI 3.0L V6 - Quattro

Diesel

Due by distance

  1. 60,000 km

    Full transmission fluid and filter service - a key milestone for long-term gearbox longevity.

  2. 100,000 km

    Evaluate the suspension bushings and verify cooling system health.

  3. 150,000 km

    Monitor the DPF (Diesel Particulate Filter) system, as city driving habits can influence its lifecycle.

C8 · 2019–2026 · 55 TFSI 3.0L V6 - Quattro

Petrol

Due by distance

  1. 60,000 km

    Transmission fluid flush and spark plug replacement, keeping that V6 running at its peak.

  2. 90,000 km

    Secondary cooling system components should be inspected for weeping or wear.

  3. 120,000 km

    Full suspension refresh, particularly bushings and control arms, as NZ roads are taxing on these components.

See all 7 issues for this oneDocumented for the exact year and engine you picked.
Electrical2

0148V mild-hybrid / start-stop faults and rough restarts

In traffic let the engine stop-start several times and note whether restarts are smooth.hybrid2019 onwardElectrical
OccasionalElectrical $600–$3,000 to fix

The C8 A6 uses a 48-volt mild-hybrid system with a belt-driven starter-generator that handles the frequent engine stop-start and coasting. Owners report harsh or slow engine restarts, start-stop dropping out, and occasional 12V/48V electrical warnings, sometimes traced to the auxiliary battery or the starter-generator. It rarely leaves you stranded but can be an expensive out-of-warranty diagnosis.

Symptoms to notice

  • Harsh or delayed engine restart from stop-start
  • Start-stop stops working
  • Electrical/battery warning messages
  • Jerky low-speed coasting-to-restart

What to check

  1. In traffic let the engine stop-start several times and note whether restarts are smooth.
  2. Watch for electrical warning messages.
  3. Ask whether the auxiliary battery has been replaced and whether the mild-hybrid system has ever thrown faults.

Where to look: 48V belt starter-generator and batteries

Parts involved: 12V battery, Starter motor.

Ask the seller

  • “Does stop-start work smoothly?”
  • “Has the auxiliary/48V battery been replaced?”

02MMI dual-touchscreen software glitches and blank screens

Sit in the car and work through both screens - reversing camera, phone pairing, climate, and let it sit to see if anything reboots.2019 onwardElectrical
OccasionalElectrical $0–$2,500 to fix

The C8 A6's twin-touchscreen MMI can freeze, reboot, or go black, and features such as reversing camera, phone connection or climate control (which lives in the lower screen) can drop out until a restart or software update. It is usually a software/module issue rather than a wiring fault, but a persistently faulty screen is costly out of warranty because so many functions depend on it.

Symptoms to notice

  • Screen freezes, reboots or goes black
  • Reversing camera or CarPlay dropping out
  • Climate/haptic controls unresponsive
  • Random warning chimes

What to check

Sit in the car and work through both screens - reversing camera, phone pairing, climate, and let it sit to see if anything reboots. Ask whether the infotainment software is up to date and whether screens have ever been replaced.

Where to look: MMI dual touchscreens in the centre dash

Ask the seller

  • “Do both screens work reliably without freezing?”
  • “Is the infotainment software up to date?”
Body, brakes, suspension & interior1

03Adaptive 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.2011–2023SuspensionRead the full fault: symptoms, where to look, what to ask the seller
Depends on the exact engine — 4 moreDocumented for a specific engine we could not confirm from what you picked. Check the engine code on the car.
Engine, transmission & cooling4

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 onwardEngine
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.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

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

  1. Cold-start the vehicle from overnight-cold and listen for chain rattle from the top of the engine in the first 10 seconds.
  2. Scan for camshaft correlation fault codes on both banks.
  3. Review oil service history — the DKNA requires 0W-20 long-life specification oil changed no later than every 15,000 km under Australasian conditions.
  4. 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.diesel2015–2023Engine
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.

A single common-rail diesel fuel injector photographed against a plain background.Example of the part — not this vehicle

A common-rail diesel injector. Contamination damages the nozzle at the tip.

Panoha · CC BY-SA 3.0 · Wikimedia Commons

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

  1. Scan for P20EE (SCR catalyst efficiency below threshold), P2201/P2202 (NOx sensor), and P204F (reductant system performance) codes.
  2. Check the AdBlue tank level and inspect the filler neck for crystallised AdBlue (white powdery residue indicating past overfill or contamination).
  3. 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.petrol2011–2023Engine
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?”

042.0 TFSI crankcase breather (PCV) and coolant thermostat weeps

Check the idle is smooth and look for oil residue around the top of the engine and coolant staining at the front.petrol2019 onwardEngine
OccasionalEngine $500–$1,500 to fix

Can't confirm for this car

The C8 A6's 2.0 TFSI is generally strong, but the plastic crankcase breather/PCV and the integrated thermostat-and-water-pump module are the common leak points as the car ages - the PCV can cause rough running and oil misting, the coolant module can weep. These are the routine ageing items on an otherwise reliable engine; there is no widespread catastrophic fault on the C8 four-cylinder.

An annotated photograph of an automotive engine thermostat identifying the wax capsule and both disc valves.Example of the part — not this vehicle

A double-valve engine thermostat, labelled: the wax capsule is what sticks.

Dougsim · CC BY-SA 3.0 · Wikimedia Commons

Symptoms to notice

  • Rough idle or occasional misfire
  • Oil misting around the breather
  • Slow coolant loss
  • Whistling/hissing at idle (PCV)

What to check

  1. Check the idle is smooth and look for oil residue around the top of the engine and coolant staining at the front.
  2. Ask about any breather or coolant module work.
  3. A scan showing lean/misfire codes points at the PCV.

Where to look: Crankcase breather/PCV on the engine; thermostat module at the front

Parts involved: PCV / oil separator, Thermostat.

Ask the seller

  • “Any breather (PCV) or coolant leak work done?”
  • “Is the idle smooth and coolant level stable?”
Other Audi A6 engines and years27 documented issues that do not apply to the one you picked.
Engine, transmission & cooling19

012.0 TDI CGLC Balance Shaft Chain Failure

Request full oil service history — intervals must have been under 10,000 km with VW 507.00 specification oil for CGLC health.diesel2011–2018Engine
CommonEngine $8,000–$22,000 to fix

Does not apply

The EA189 2.0 TDI (engine code CGLC) uses a secondary balance shaft chain driven off the crankshaft to eliminate second-order vibration. This chain, its hydraulic tensioner, and plastic guide rails are prone to stretching and failure at high mileage or under extended oil service intervals. As the chain elongates it takes the balance shaft out of phase, causing severe engine vibration and knock. Complete chain or guide failure allows the balance shaft to seize, destroying the oil pump drive integrated into the balance shaft module. Sudden oil pressure loss results in catastrophic main bearing and connecting rod damage requiring engine replacement.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Severe engine knock or heavy low-frequency vibration particularly under load
  • Rattling or slapping noise from lower front of engine at start-up
  • Oil pressure warning light illuminating suddenly during driving
  • Check engine light with crankshaft or balance shaft correlation fault codes
  • Engine stalls without warning or will not restart after balance shaft seizure

What to check

  1. Request full oil service history — intervals must have been under 10,000 km with VW 507.00 specification oil for CGLC health.
  2. Scan for crankshaft and balance shaft correlation fault codes.
  3. Listen for any rattling from the lower front engine area.
  4. Ask specifically about any history of rough running, vibration, or oil pressure warnings.
  5. On high-mileage examples above 150,000 km consider pre-purchase inspection with balance shaft chain access.

Where to look: Lower front of engine block — balance shaft chain runs between crankshaft sprocket and balance shaft module, accessed via oil sump removal

Parts involved: Timing chain.

Ask the seller

  • “What has the oil change interval been and was VW 507.00 specification oil always used?”
  • “Has the vehicle ever shown engine knock, heavy vibration, or an oil pressure warning?”
  • “Has the balance shaft chain, tensioner, or guides ever been replaced or inspected?”
  • “Has the car ever stored crankshaft or balance shaft correlation fault codes?”

023.0 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.diesel2011–2019Engine
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.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

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

  1. 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.
  2. Pull oil filler cap and inspect for metal swarf.
  3. Request full service history showing correct oil specification (VW 507.00).
  4. 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?”

03Twin turbo failure from coked oil feed lines and screens (2.7T biturbo)

Ask for invoices showing turbos or turbo oil lines have been replaced and whether the newer larger-diameter feed lines were fitted.petrol1999–2004EngineRead the full fault: symptoms, where to look, what to ask the seller

042.0 TFSI Cam Follower / HPFP Wear

Inspect the follower base for a wear groove or central perforation — a serviceable follower is flat and smooth.petrol2008–2015EngineRead the full fault: symptoms, where to look, what to ask the seller

052.7 / 3.0 TDI rear timing chain tensioner rattle (pre-2008 risk)

Insist on a cold first start and listen carefully at the front and rear of the engine for a chain rattle.diesel2004–2011Engine
OccasionalEngine $4,000–$9,000 to fix

Does not apply

The C6 V6 TDI drives its timing chains from the flywheel/rear end of the engine, and earlier (pre-2008) upper tensioners can wear and let the chain go slack, producing a cold-start rattle. If the chain jumps, valve-to-piston contact causes major internal damage, and because the chains are at the back of the engine the repair means removing the gearbox. Later revised tensioners are more robust; a rattling cold start on an early car should be taken seriously.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Metallic rattle on cold start that fades as it warms
  • Rattle when switching off
  • Camshaft correlation fault codes
  • Rough running after a rattle event

What to check

Insist on a cold first start and listen carefully at the front and rear of the engine for a chain rattle. On a pre-2008 car this is the key check. Ask for evidence the chains/tensioners have been renewed with updated parts.

Where to look: Timing chains at the rear (gearbox end) of the engine

Parts involved: Timing chain.

Ask the seller

  • “Does it rattle on a cold start?”
  • “Have the timing chains or tensioners been renewed?”

06S-Tronic DL501 Mechatronic Unit Failure

Test all gear positions including reverse for smooth engagement.2011–2018TransmissionRead the full fault: symptoms, where to look, what to ask the seller

07Timing belt, tensioner or water pump failure destroying valves (1.8T 20v, 2.4/2.8 30v V6, 2.7T biturbo)

Ask for a dated invoice showing the timing belt, tensioner, idlers and water pump were replaced, with the odometer reading.petrol1997–2004EngineRead the full fault: symptoms, where to look, what to ask the seller

08Judder, slipping and control unit failure (01J Multitronic (A6 C5))

Check the dash gear display is steady and not flashing at any point during the drive.2000–2004TransmissionRead the full fault: symptoms, where to look, what to ask the seller

09Oil sludge and clogged oil pickup screen starving the engine (1.8T 20v AEB/APU/AWT)

petrol1997–2004EngineRead the full fault: symptoms, where to look, what to ask the seller

102.0 TFSI Timing Chain Tensioner Failure

Cold-start the engine from fully cold and listen for a chain rattle from the front timing cover before oil pressure builds.petrol2008–2018EngineRead the full fault: symptoms, where to look, what to ask the seller

112.0 TFSI EA888 Excessive Oil Consumption

Check the oil dipstick and ask the owner to demonstrate how much oil is used between services.petrol2008–2012EngineRead the full fault: symptoms, where to look, what to ask the seller

12Multitronic CVT judder and failure (front-wheel-drive A6)

First establish whether the car is FWD (Multitronic) or quattro.2000–2015TransmissionRead the full fault: symptoms, where to look, what to ask the seller

13Camshaft lobe and rocker follower wear (2.5 TDI V6 AFB/AKE)

diesel1997–2004EngineRead the full fault: symptoms, where to look, what to ask the seller

143.2 FSI Valve Stem Seal Failure & Oil Burn

petrol2004–2011EngineRead the full fault: symptoms, where to look, what to ask the seller

152.0 TDI DPF Premature Clogging

Check for associated EGR valve fault codes (P0401, P0404) or differential pressure sensor codes that would prevent regeneration.diesel2004–2011EngineRead the full fault: symptoms, where to look, what to ask the seller

163.0 TDI EGR Cooler Internal Crack and Coolant Ingress

Check the coolant expansion tank level at operating temperature — an unexplained drop without external leaks is the primary indicator.diesel2011–2018Cooling
OccasionalCooling $1,800–$4,500 to fix

Does not apply

The exhaust gas recirculation cooler on the CDUD and CKVB 3.0 TDI engines is an aluminium heat exchanger that transfers heat from recirculated exhaust gas into the engine coolant. Thermal cycling causes the internal matrix to crack, initially causing a small coolant loss with white exhaust smoke at idle. As the crack grows, coolant enters the intake manifold and can cause a hydrostatic lock event or contaminate the EGR valve. In severe cases the intake manifold must also be replaced due to coolant pooling and corrosion.

Symptoms to notice

  • Slow, unexplained coolant loss with no visible external leak on the ground
  • White or grey steam from the exhaust at idle or light throttle, distinct from normal condensation
  • Sweet smell from the exhaust on cold mornings indicating coolant combustion
  • Engine running rough after the car has sat — pooled coolant in the intake manifold
  • P0401 (EGR flow insufficient) codes as the cooler restriction increases

What to check

  1. Check the coolant expansion tank level at operating temperature — an unexplained drop without external leaks is the primary indicator.
  2. Look for white steam from the exhaust at idle on a warm engine.
  3. Check the intake manifold floor near the EGR connection port for pooled coolant or corrosion staining.
  4. If a workshop inspection is possible: Pressure test the cooling system and monitor for a drop while the EGR system is active.
  5. Remove and inspect the EGR cooler inlet/outlet for coolant residue.

Where to look: Rear of the engine valley between the two cylinder banks, connected to the EGR valve and intake manifold

Parts involved: EGR valve.

Ask the seller

  • “Has the EGR cooler ever been replaced or inspected, and has the coolant level ever dropped unexpectedly?”
  • “Has the engine ever produced white smoke at idle or been diagnosed with any coolant system fault?”

172.7 / 3.0 TDI EGR cooler soot clogging and coolant seepage

Have it scanned for EGR flow codes.diesel2004–2011EngineRead the full fault: symptoms, where to look, what to ask the seller

182.0 TFSI timing chain tensioner rattle (EA888)

Get a genuinely cold first start and listen at the front of the engine.petrol2011–2018Engine
CommonEngine $1,800–$3,500 to fix

Does not apply

The C7 A6 2.0 TFSI shares the EA888 chain-tensioner weakness of its A4/A5/Q5 siblings, especially on earlier build cars. A worn tensioner lets the chain go slack when parked, producing a cold-start rattle and, in the worst case, a jumped chain and bent valves. Check exactly as you would on any EA888 - the cold first start tells the story.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Diesel-like rattle for 1-3 seconds on cold start
  • Rattle on shut-down
  • Camshaft/crankshaft correlation codes
  • Rough idle

What to check

  1. Get a genuinely cold first start and listen at the front of the engine.
  2. A sustained cold-start rattle is a serious warning.
  3. Ask for proof the chain kit and updated tensioner have been fitted.

Where to look: Timing chain at the rear of the engine

Parts involved: Timing chain.

Ask the seller

  • “Has the timing chain/tensioner been replaced?”
  • “Does it rattle when cold?”

193.0 TFSI supercharged coolant leaks and water pump failure

Check the coolant level and look into the engine 'V' for pink/orange staining.petrol2011–2018Cooling
CommonCooling $1,200–$3,000 to fix

Does not apply

The C7 A6 3.0 TFSI is supercharged, with coolant hoses and an intercooler tucked under the supercharger in the engine 'V'. The water pump (often with a plastic impeller) fails and the buried coolant lines leak, and access is poor so labour is significant. It is one of the most-reported issues on this engine; a car that runs warm or loses coolant needs proper investigation before purchase.

Symptoms to notice

  • Coolant loss / low coolant warnings
  • Temperature creeping up in traffic
  • Sweet coolant smell
  • Coolant residue in the engine 'V'

What to check

  1. Check the coolant level and look into the engine 'V' for pink/orange staining.
  2. On the drive watch the temperature gauge in slow traffic.
  3. Ask whether the water pump and coolant lines under the supercharger have been done.

Where to look: Water pump and coolant hoses under the supercharger, in the engine 'V'

Parts involved: Water pump.

Ask the seller

  • “Has the water pump been replaced?”
  • “Does it lose coolant or run warm in traffic?”
Electrical2

01Coil-on-plug ignition coil failure and misfire (1.8T 20v, 2.7T biturbo)

Start the car from cold and watch the engine warning light: it should go out a few seconds after starting and must never flash.petrol2000–2004ElectricalRead the full fault: symptoms, where to look, what to ask the seller

02Instrument cluster display pixel failure (C5 driver information display)

1997–2004Electrical
Very commonElectrical $300–$800 to fix

Does not apply

The monochrome LCD in the middle of the C5 A6 instrument cluster (driver information display showing radio, trip computer, gear and warnings) loses pixels and lines over time because of a failing ribbon connection and display. It becomes hard or impossible to read warning messages, the odometer segments or the selected gear. Audi offered no fix; the usual repair is sending the cluster to a specialist for a new display, which also keeps the original odometer reading.

Symptoms to notice

  • Missing lines or blocks of pixels in the centre display
  • Faded or unreadable trip computer, radio or gear display
  • Warning messages partly missing

What to check

  1. Turn the ignition on and look closely at the centre display between the dials: scroll through the trip computer and check every line of text is complete with no missing columns or blocks.
  2. Check the odometer and gear display read clearly.
  3. Ask whether the cluster has been replaced or repaired, and if so compare the odometer against the service history and warrant of fitness records so a swapped cluster has not changed the km.
  4. If a workshop inspection is possible: check the cluster coding and odometer against the engine control unit with a scan tool.

Where to look: Centre of the instrument cluster behind the steering wheel

Ask the seller

  • “Has the instrument cluster ever been repaired or replaced?”
  • “If so, was the odometer reading carried over and is there paperwork?”
Body, brakes, suspension & interior5

01Air Suspension Front Strut Air Bladder Failure

Park on a level surface overnight and check front ride height in the morning before starting.2011–2018Suspension
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

  1. Park on a level surface overnight and check front ride height in the morning before starting.
  2. Listen for compressor running when the car is parked.
  3. Spray soapy water around the base of each front strut and along the rubber bellows convolutes to identify air bubbles indicating leaks.
  4. Scan suspension module fault codes via VCDS.
  5. 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.2011–2018SuspensionRead the full fault: symptoms, where to look, what to ask the seller

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.2011–2018SuspensionRead the full fault: symptoms, where to look, what to ask the seller

04Worn control arm bushes and ball joints (A6 C5 front multi-link)

On the test drive, go slowly over speed bumps and rough patches with the windows down and listen for clunks or knocks from the front.1997–2004SuspensionRead the full fault: symptoms, where to look, what to ask the seller

05Front multi-link control-arm bush and ball-joint wear

On the test drive listen for knocks over rough roads and feel whether the steering tramlines or wanders.2000–2011Suspension
Very commonSuspension $900–$2,500 to fix

Does not apply

The C5/C6 A6 uses a multi-link front suspension with numerous alloy control arms whose bushes and ball-joints wear out, producing knocking over bumps and vague steering. It is a defining wear area for these cars - a full arm kit per side is a common job by 150,000 km. Not dangerous if caught, but a clunky, wandering front end is a bargaining point and, if ignored, chews tyres.

The front wheel of a car splayed outward with the lower control arm hanging down after a ball joint separation.Example of the part — not this vehicle

A separated lower ball joint: the control arm has dropped and the wheel has splayed out under the guard.

Elfix · CC0 · Wikimedia Commons

Symptoms to notice

  • Knocking or clunking over bumps and speed humps
  • Vague or wandering steering
  • Uneven front tyre wear
  • Steering wheel shimmy

What to check

  1. On the test drive listen for knocks over rough roads and feel whether the steering tramlines or wanders.
  2. Look at the front tyres for uneven/inner-edge wear.
  3. Ask when the front control arms were last replaced.

Where to look: Front suspension control arms, both sides

Parts involved: Ball joint.

Ask the seller

  • “When were the front control arms last replaced?”
  • “Does the front end knock over bumps?”
Fluid leaks1

01Cam chain tensioner gasket and valve cover oil leaks onto the exhaust (2.4/2.8 30v V6, 2.7T)

petrol1997–2004Fluid Leaks
Very commonFluid Leaks $600–$1,600 to fix

Does not apply

The 30v V6 family has a small chain linking the two camshafts in each head, with a tensioner sealed by a rubber gasket and half-moon plugs, and these plus the valve cover gaskets harden and leak oil onto the exhaust manifolds. It gives a burning oil smell in the cabin and oily heads, and a failed crankcase breather (the vacuum booster / PCV valve) builds pressure that makes the leaks worse. It is normally fixed alongside the timing belt because the covers come off anyway; left alone it is a fire and smoke nuisance and can drip onto the belt.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Burning oil smell in the cabin or after stopping
  • Wisps of smoke from the back or sides of the engine when hot
  • Oil wet around the edges of the cylinder head covers
  • Oil level dropping between services with no blue smoke

What to check

With the bonnet open and a phone torch, look along the joint between each cylinder head and its valve cover, especially at the front of each head near the timing belt end, for wet oil, black grime or oil pooling. Sniff for burning oil after the test drive and watch for smoke rising from the engine bay while it idles hot. Check the ground where the car has been parked. If a workshop inspection is possible: have the engine covers and timing cover taken off to check the cam tensioner gaskets, half-moon seals and the crankcase breather valve.

Where to look: Top of both cylinder heads at the valve covers; front end of each head where the cam chain tensioner sits

Parts involved: Timing chain, Rocker / valve cover.

Ask the seller

  • “Have the cam tensioner gaskets and valve cover gaskets been replaced?”
  • “Was the crankcase breather / PCV valve replaced at the same time?”
  • “Do you notice a burning smell after a drive?”

Audi A6 faults in detail

Narrowed to the Audi A6 · 2020. Each of these has its own page: the symptoms, where to look, what to ask the seller and what the repair costs. Free, no account needed.

Adaptive Air Suspension Compressor and Height Sensor FailureMajor · Suspension

What these repairs cost on other cars

Some of the Audi A6’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 faultsAudi A343 documented faultsAudi A525 documented faultsAudi Q520 documented faultsAudi S318 documented faultsAudi TT17 documented faults

Audi A6 buyer questions

Is the Audi A6 reliable?

Like any used car, it depends on the specific example and its service history. Across the 34 documented faults for the Audi A6, the recurring problem areas are engine, transmission, and suspension. A Audi A6 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 A6?

We've catalogued 34 known faults for the Audi A6, covering engine, transmission, and suspension. All 34 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 A6?

Most single repairs on the Audi A6 fall between $1,200–$4,500 at NZ independent-workshop rates. Some of the 34 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 A6?

Yes. A Audi A6 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.