Audi RS4 Avant

In the 2.9 TFSI BiTurbo (DECA), rocker arm bearing rollers can fall out of the cylinder head and end up in the oil pan. Early production years (up to approx. 2019) are especially affected. A revised design with thicker bearing rollers was introduced. No official recall, but serious consequences are possible.

Symptoms: Knocking or rattling noises from the cylinder head, metal particles in the engine oil, sudden power loss, engine fault codes

As a pure direct injector without port injection, the EA888 DECA builds pronounced soot deposits on the intake valves. Crankcase ventilation oil mist and EGR gases thermally bond to the valve heads. Cleaning from 40,000–60,000 km onwards is recommended.

Symptoms: Creeping power loss, stumbling under partial load, rougher idle, increased fuel consumption especially in city traffic

The 2.9 TFSI DECA shows elevated oil consumption with spirited driving due to high thermal loads and boost pressures. Coked piston rings worsen the problem. Regular oil level checks between service intervals are essential on the RS4/RS5 B9.

Symptoms: Dropping oil level between oil changes, occasional blue smoke under hard acceleration, light oil smell

Both turbochargers of the 2.9 TFSI DECA can lose shaft seals at high mileage or with aggressive use. Oil consumption rises, oil mist enters the intake. Since both turbos are on the inner engine side, removal is very labour-intensive.

Symptoms: Increasing oil consumption, light blue smoke, oil traces in the intercooler, whistling under load

The 2.9 TFSI DECA uses a timing chain system where tensioners wear and can cause rattling on cold start. High power output and spirited use increase the load on the timing drive. Early tensioner replacement prevents chain elongation.

Symptoms: Rattling on cold start that subsides at operating temperature, camshaft fault code, MIL with timing chain fault

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.