Reliability guide for used Audi A5, S5 and RS5 B9 cars
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Produced between 2015 and 2023, the Audi A5 B9 is the fifth generation of the premium family sedan, available as a sedan, Avant (estate), and Allroad. The sporty S5 (supercharged 3.0 TFSI V6) and RS5 (twin-turbo 2.9 TFSI V6) versions offer a distinctly sporty character, while also benefiting from significant technological advancements compared to the B8.
Overall, the A5 B9 is more reliable than the previous generation , but some engines and technical elements deserve attention when buying.
Highlights of the A5 B9
- The quality of the finish has improved significantly: modern interior, premium materials.
- Excellent comfort and soundproofing, especially in the high-end finish.
- Wide range of petrol and diesel engines, with mild hybrid (MHEV) versions.
- Dynamic road handling, especially in quattro.
- High-performance and modern S4 and RS4 sports versions.
Reliability by engine
Essence
1.4 TFSI (150 hp)
- Overall reliable and economical.
- Key points:
- Water pump/thermostat : frequent fluid leaks around 100,000 km.
- Ignition coils that can fail prematurely.
- Turbocharger : few reported cases, but expensive replacement in case of seizure.
- Well suited for short rides, but lacks power on the road.
2.0 TFSI (190-245 hp)
- A versatile, high-performance and fuel-efficient engine.
- Recurring flaws:
- Fragile water pump → coolant loss (bill between €500 and €900).
- Thermostat that remains open → engine that struggles to heat up.
- Oil consumption : rare but still reported on some examples <2018.
- High-pressure injectors sensitive to fouling → to be monitored in case of difficult starts.
- Significantly improved reliability after 2017 thanks to improvements in injection and segmentation.
Audi S5 B9 – 3.0 TFSI V6 (354 hp)
- Excellent compromise between performance and reliability, but not without weaknesses:
- Water pump and thermostat : frequent failures around 80-100,000 km.
- Chain tensioners : rattling when cold → risk of elongation if not treated.
- Fuel pressure sensor sometimes faulty → loss of power.
- Coils and spark plugs are sensitive if driven sportily repeatedly.
- Moderate oil consumption (1L/5000 km) sometimes observed.
- With proper maintenance, it's a reliable and enjoyable engine.
Audi RS5 B9 – 2.9 TFSI V6 biturbo (450 hp)
- Great potential and good robustness, but beware of:
- Hoses and cooling system → overheating possible if used intensively.
- Turbos : risk of wastegate fouling, loss of pressure at high mileage.
- High-pressure injectors sensitive to fouling (cleaning/removal sometimes necessary).
- Catalytic converters can become clogged with excessive urban driving.
- Faulty sensors (pressure, intake temperature) trigger engine warning lights.
- Generally reliable engine, but best suited for those with rigorous maintenance and a clear history.
Diesel
2.0 TDI (150-190 hp)
- Simple and widespread, but not without weaknesses:
- EGR : frequent clogging in urban use → loss of power / engine warning light.
- DPF : risk of saturation on short journeys (costly cleaning or replacement).
- Injectors : more sensitive after 150,000 km, symptoms = difficult starting / clicking.
- Water pump sometimes fragile (coolant leaks).
- On the road, it's a safe bet, especially the post-2018 versions with MHEV.
3.0 TDI V6 (218-272 hp and 347 hp for the S4 diesel)
- Considered one of the best engines in the B9 range.
- Points to be aware of:
- The timing chain is solid, but a metallic noise at startup should raise concern.
- EGR : always a sensitive issue, especially in urban use.
- DPF : can become clogged if poorly regenerated.
- EGR cooler : known leaks on some units → loss of coolant.
- Overall, reliable and durable if used appropriately (highway/long journeys).
Other known issues (all versions)
- S tronic / Tiptronic gearboxes : generally reliable, but check maintenance history.
- Power steering : rare leaks on some B9 models.
- Electronics : MMI sensors, driving assistance and parking radar can sometimes be temperamental.
- Front axle : silent blocks and suspension arms can wear out, especially on sport versions.
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Enhance the exterior design with our sporty grilles , carbon mirror caps and body kits inspired by the S5/RS5:
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Which model should I choose?
- Daily use : 2.0 TDI post-2017 or 2.0 TFSI post-2017 (improved reliability).
- Reliable V6 diesel : 3.0 TDI, excellent performance/longevity ratio.
- Balanced sports car : S5 B9, powerful and relatively reliable supercharged V6 engine.
- Modern icon : RS5 B9, high-performing and technologically advanced, rigorous maintenance recommended.
