ExhaustHigh
DPF and AdBlue faults on 2.0 and 3.0 TDI
- Typically appears
- 80,000+ miles
- What to inspect
- Check the AdBlue countdown and run to temperature
2014–2025 Audi A6 · common problems & known faults
The classic executive saloon and Avant. Most arrive as ex-fleet cars with big motorway miles and full history.
Compiled & reviewed by the VehicleFaults Research Team · last reviewed August 2026
Quick answer
The most commonly reported faults on the 2014–2025 Audi A6 are DPF and AdBlue faults on 2.0 and 3.0 TDI, Air suspension on Avant models leaking and dropping and S tronic and multitronic judder and hesitation. 4 of the documented issues are rated high severity · inspect these first. Full inspection points, onset mileage and what to check are listed below.
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Build the inspection planReliability snapshot
Based on the documented faults on this page for the Audi A6.
3.7/ 10
- Critical
- 0
- High
- 4
- Medium
- 3
- Low
- 1
Guidance only · reflects reported patterns, not a specific car's condition.
Known faults to check
SuspensionHigh
Air suspension on Avant models leaking and dropping
- Typically appears
- 80,000+ miles
- What to inspect
- Check overnight ride height on air-sprung cars
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Build the inspection planTransmissionHigh
S tronic and multitronic judder and hesitation
- Typically appears
- 80,000+ miles
- What to inspect
- Test from cold in slow traffic
ElectricalMedium
MMI, matrix headlight and sensor faults
- Typically appears
- Age-related
- What to inspect
- Test the lights, screens and all driver assistance
EngineHigh
Timing chain tensioner rattle on 3.0 TDI
- Typically appears
- 70,000-100,000 miles
- What to inspect
- Perform a completely cold start with the bonnet open. Listen closely to the rear of the engine block for a distinct metallic rattling sound lasting 3 to 5 seconds before oil pressure builds.
CoolingMedium
Thermostat housing and water pump leaks on V6 engines
- Typically appears
- 50,000-80,000 miles
- What to inspect
- Shine a torch down the front of the engine block, directly beneath the intake manifold. Look for pooled coolant or a crusty, pink residue indicating a slow leak from the housing.
BodyworkLow
Fuel filler flap locking solenoid failure
- Typically appears
- 4-6 years
- What to inspect
- Lock and unlock the car using the key fob, then press the fuel filler flap. It should spring open freely. If it remains locked or requires excessive force, the actuator solenoid has failed.
Engine MountsMedium
Active engine mount failure causing cabin vibration
- Typically appears
- 60,000-90,000 miles
- What to inspect
- Start the engine, apply the footbrake firmly, and shift the transmission into Drive. Feel for harsh, rhythmic vibrations transferring through the steering wheel and driver's seat, indicating collapsed active mounts.
Inspecting a Audi A6?
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Build my inspection planFrequently asked questions
Are ex-fleet A6s good stock?
Yes. Motorway miles with documented servicing are far kinder than low-mileage town use.
What is the hidden cost?
Matrix headlights and air suspension. Both are four-figure jobs at retail prices.
Saloon or Avant?
Avant retails faster in the UK and holds a price premium with family buyers.
What should dealers know about the 48V mild-hybrid system on C8 models?
The C8 generation introduced a 48V mild-hybrid system across most engines. The belt starter generator is a known weak point, often failing and triggering a red charging system fault on the dash. Replacement is expensive and requires dealer-level software calibration, so ensure no electrical warnings are present.
Do the 2.0 TDI engines use a timing belt or a timing chain?
The popular 2.0 TDI engines use a timing belt, unlike the 3.0 V6 TDI which is chain-driven. Audi UK officially recommends replacing the 2.0 TDI timing belt and water pump every 140,000 miles, but most independent specialists strongly advise replacement at 80,000 miles or five years to prevent catastrophic failure.
How does Quattro with Ultra technology differ from traditional Quattro?
Introduced on later C7 and most C8 models, Quattro with Ultra is a part-time all-wheel-drive system. It uses two clutches to decouple the rear prop shaft and differential to save fuel. It requires specific fluid changes every 40,000 miles to prevent mechanical binding or juddering during tight, low-speed cornering.
Sources & further reading
Faults are compiled from documented recalls, technical bulletins, owner reports and mechanic sources, then reviewed for accuracy. This is guidance only · not a substitute for a professional inspection.
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