Audi RS5
The CFSA is Audi's farewell gift from the naturally aspirated V8 — 8,250 rpm rated speed, 450 PS without a turbo. The character is the opposite of a BiTurbo: the engine demands revs and rewards with a sound no production family car offers any more. Double throttle body in the intake: soft down low, sharp up top. Direct injection (FSI) is the structural weakness: without fuel washing over the intake valves, their backs coke up from blow-by oil vapour. Walnut blasting every 50,000–70,000 km is mandatory. The variable intake manifold with flaps tends to rattle from oil deposits — bolts can come loose and fall into the engine. Timing chain fundamentally robust, needs clean oil and short change intervals.
RS5 Coupé — NA V8 in the best-looking B8 body
Same 450 hp V8 as the RS4 B8, but in a coupé. Visually the most beautiful high-revving Audi, acoustically a revelation. Heavier than necessary, not as sharp as an M3, but the sound compensates. The coupé is the more fitting body for this engine than the wagon.
Engine Weaknesses 9
CFSA uses simplex chains on the gearbox side. Although more robust than the BBK predecessor, tensioners and guides are wear items. Engine removal mandatory for a full repair. Significantly more durable with regular short oil change intervals.
Symptoms: Rattle on cold start, timing chain noise at low revs, engine warning light
The CFSA revs to 8,250 rpm as a high-revving naturally-aspirated engine. Con rod bearings are under extreme stress. Neglected oil changes or poor-quality oil risk bearing wear. Preventive replacement at 80,000–100,000 km is discussed.
Symptoms: Knocking from the engine at operating temperature, increasingly loud rumbling at high revs, oil pressure drop
Four camshaft adjusters on the CFSA are more heavily stressed by high-rev operation up to 8,250 rpm than a normal V8. Oil quality and short change intervals are critical for longevity.
Symptoms: Rattle on start, camshaft fault codes, limp mode
The flaps in the variable intake manifold stick due to oil deposits from crankcase ventilation and begin to rattle. In the worst case screws or flap fragments come loose and are ingested by the engine — piston and valve damage can result.
Symptoms: Rattling or clattering from the intake area at idle and low revs, rough idle, individual cylinder misfires.
FSI deposits on intake valves documented from as early as 32,000 km, especially severe with urban use. Walnut blasting costs 600–900 € for RS4/RS5. Regular cleaning every 40,000–60,000 km recommended.
Symptoms: Power loss (up to 40 hp), rough idle, poor throttle response at low revs
RS4/RS5 with CFSA shows elevated oil consumption due to high revs and spirited use. Valve stem seals and piston rings wear. 1–2 L/1,000 km during spirited driving is normal.
Symptoms: Oil level drops noticeably, slight blue smoke after full-throttle sections, oil consumption above 1 L/1,000 km
CFSA water pump is heavily stressed in RS4/RS5 high-performance use. Failure after 100,000–140,000 km. Replace thermostat at the same time. Tight engine bay in the RS4 B8 means higher labour costs.
Symptoms: Coolant level drops, temperature fluctuations, coolant smell after driving
The FSI high-pressure pump in the CFSA can fail after 80,000–100,000 km. In the RS4/RS5 with high-performance demands this is particularly critical. Expensive replacement due to cramped engine bay.
Symptoms: Starting problems, severe power loss, hesitation under load, fuel smell
8 ignition coils in the CFSA are particularly prone to failure due to high-rev use. Motorsport-oriented use increases wear. Complete coil replacement 300–700 €.
Symptoms: Misfires, engine warning light with misfire code, hesitation on acceleration
Vehicle Weaknesses 9
The CVT Multitronic (0AW) tends to catastrophic failures around 100,000 km: juddering when pulling away, extreme rpm fluctuations and loss of reverse gear. Without regular gearbox oil changes, complete failure is likely.
A5 and Q5 models from 2008–2012 with a defective passenger airbag inflator. On deployment, uncontrolled gas pressure can release metal fragments.
Dampers and control arms wear noticeably from around 80,000 km, especially on Sport and S line suspension. A full control arm set costs €2,000–3,000; individual rear dampers around €1,000.
The soft-top mechanism hydraulic hoses become brittle and leak. Hydraulic oil collects under the trim in the boot and can saturate the exhaust heat shield.
At the transitions between underbody sealant and paint, rust bubbles form on sills and wing bases. Dirt and moisture collect behind underbody covers.
The S tronic dual-clutch gearbox shows premature clutch wear in stop-and-go traffic and when towing. Juddering when pulling away and harsh gearshifts, often fixable by software update.
TÜV inspection reports flag brake hoses on the A5 8T twice as often as the class average. From around 10 years of age rubber hoses become porous.
The window regulator mechanism frequently breaks, especially on the Coupe. The window regulator module must then be replaced completely.
The AC compressor can fail at higher mileages, especially if the AC has not been used for extended periods.