Audi S4
Supercharged V6 with 260 kW. Proven drivetrain for S4/S5 and SQ5 with linear power delivery and good throttle response.
354 hp company car — objectively fast, subjectively empty
Fast, quiet, completely sterile. Active Sound from the speakers instead of real V6 noise, steering that informs but never communicates, AWD that delivers traction without ever being noticed. Objectively better than the B7 at everything except making you feel something. The right car for a fast commute — the wrong car for a driving experience.
Engine Weaknesses 8
Early CWGD units with P-code GP0 (up to production date 06.08.2018) have poor-quality rocker arm rollers. The small bearing rollers can fall out and end up in the oil sump — camshaft and piston damage possible.
Symptoms: Combustion misfire, engine fault light, rough running, clattering noise from cylinder head.
The EA839 water pump is vacuum-controlled. On internal failure, coolant enters the vacuum system and spreads to further engine components. The old 4-bolt pulley is the prime suspect — identifiable if original pump still fitted.
Symptoms: Coolant warning light, coolant loss without external leakage, P0299 (boost pressure too low), 'drivetrain fault', 12V battery no longer charging.
The belt starter-generator (BSG) and the 48V battery can fail, especially on vehicles before 2021 without the protective cover over the control unit. Diagnosis and calibration required after replacement.
Symptoms: '48V system fault' in display, start-stop disabled, no recuperation, rough or delayed starting, limp mode.
Beyond water pump failure, EA839 engines also show coolant loss from seal failures elsewhere in the cooling system. Regular coolant level checks important.
Symptoms: Coolant level drops without visible leakage, overheating warning, coolant smell in engine bay.
Turbocharged version of the EA839 without supercharger, but still direct injection: oil mist from crankcase ventilation settles as coke on intake valves.
Symptoms: Hesitation, power loss at part throttle, cold-start problems, rough idle.
The EA839 CWGD shows elevated oil consumption during spirited driving and high revs from piston rings. Vehicles frequently on track or driven at full throttle are particularly affected.
Symptoms: Regular top-ups required, oil consumption above 0.5 L/1,000 km during spirited use.
The EA839 CWGD responds to worn spark plugs with misfires and elevated fuel consumption. Change interval of 30,000–40,000 km recommended for spirited use.
Symptoms: Hesitation under load, misfire fault codes, increased consumption, slight power loss.
Excessive manufacturing tolerances between injector lines and rail cause petrol vapour leaks. Fuel smell inside the car is the typical symptom.
Symptoms: Petrol smell inside after switching off, especially with a warm engine.
Vehicle Weaknesses 7
Defective coolant valves cause coolant loss that can silently lead to overheating. Temperature sensors and thermostat housing are a weak point from 60,000–100,000 km.
The rubber bushings in the upper control arms wear prematurely, in some cases from as early as 60,000–80,000 km. The issue is said to have been fixed only with the 2019 facelift.
Certain 19-inch tyre combinations on the B9 lead to premature wear on the inner flanks. The cause is a suspension setup not optimally tuned for larger wheels. Regular wheel alignment recommended.
The S tronic dual-clutch gearbox judders when pulling away and at low speeds. The mechatronics unit can become defective.
Water pump and thermostat housing typically fail between 60,000 and 170,000 km. A well-known weak point on the 2.0 TFSI and 2.0 TDI.
The S tronic dual-clutch gearbox exhibits a known juddering in D and R at idle that Audi classes as within the state of the art. Diesel variants may additionally creep.
The MMI infotainment system frequently exhibits Bluetooth connectivity problems in facelift models: choppy music playback, missed ringtones. Software updates do not always provide a permanent fix.
Reports & Tests
314 owner complaints filed with NHTSA (2015–2026). Most reported: Electrical (121), Other (92), Engine (49).