Audi RS4 4.2 FSI V8 B7

The DRC system hydraulically links diagonally opposed dampers to control body roll. Seal deterioration causes oil leaks and pressure loss, typically presenting as uneven ride height, clunking noises, or noticeably degraded handling. Audi extended the DRC warranty to 5 years / 75,000 miles in the UK due to the volume of complaints. Replacing one failed damper often requires its diagonal partner too, as they share hydraulic pressure. OEM repair for a pair runs around €1,500-2,000 at a specialist. Many owners convert to aftermarket coilovers (Bilstein B14, KW V3) for €1,800-3,000 fitted, which eliminates the DRC system entirely and is the most popular long-term solution. Specialist equipment is needed to repressurize DRC dampers, limiting repair options.

The 4.2 FSI uses direct injection, meaning fuel does not wash over the intake valves. Carbon deposits accumulate progressively, especially with short trips and low-rpm driving. Symptoms include rough idle, hesitation, reduced power, and increased fuel consumption. Cleaning requires intake manifold removal and manual walnut blasting or scrubbing of all 8 ports. Most specialists charge €800-1,500 for the job, which takes 8-10 hours. This is effectively a maintenance item needed every 40,000-60,000 km depending on driving style. Regular spirited driving and quality fuel help slow the buildup but cannot prevent it entirely.

The oil cooler sits at the bottom of the centre grille area. Its connecting pipes are prone to corrosion, particularly the crimped connections. Symptoms are oil drips under the car, often noticed on the front subframe or undertray. The cooler and both lines typically need replacing together. Parts cost around €400-600 from Audi, with upgraded aftermarket kits available from specialists like Forge for similar money. Labor adds another €400-600. This issue is age-related and affects most B7 RS4s that have not already had the repair, especially in salt-exposed climates.

The RS4 engine uses a network of vacuum pipes controlling intake manifold flaps, airbox changeover flap, and exhaust valve flaps. Rubber vacuum lines become brittle and crack with heat and age, creating leaks that disable these systems. The ECU responds by reducing timing for engine protection, causing noticeable power loss. Diagnosis involves pressure testing the vacuum circuit. Replacement of all vacuum lines is straightforward but time-consuming. The intake manifold flap solenoid (located at the front of the manifold) also commonly fails, triggering P2015/P2020 fault codes. Aftermarket billet aluminum linkage kits are available as a more durable replacement.

The RS4 has 8 individual ignition coils, and the original units have a higher-than-normal failure rate. Audi released updated part numbers to address early failures. Symptoms include misfires, rough running, and check engine light. Individual coils cost around €30-50 each. If a misfiring cylinder sends unburnt fuel through the exhaust, it can damage one of the two catalytic converters (€500-1,000 each to replace). Most owners replace all 8 coils preventively. Total cost for 8 new coils fitted is around €300-500 at a specialist.

The 6-speed manual gearbox itself is robust and rarely gives trouble. However, the clutch and dual-mass flywheel wear out with normal use, particularly with spirited driving or track use. The clutch pedal can also develop a sticky feel during high-rpm shifts. Replacement requires transmission removal (8-9 hours labor). Parts cost €800-1,200 for clutch kit plus flywheel, with total fitted cost of €2,000-3,500. Clutch life varies enormously with driving style but most owners report 80,000-130,000 km before replacement is needed.

The RS4 has auxiliary radiators located behind the front bumper on each side, in addition to the main radiator. These develop leaks over time, typically at the crimped end tank connections. Symptoms include pink coolant dripping from below the front wheel arches and steam from the foglight area. Replacement requires bumper removal. Each radiator costs around €150-250 for the part. Some owners delete one of the two auxiliary radiators if it is not essential for their climate, though this is not recommended for hot climate use.

Both valve cover gaskets can develop leaks as they age, with oil seeping into the spark plug wells. Pre-2008 cars had a known design issue where the driver-side valve cover did not fully cover one spark plug hole. Audi later redesigned the cover for better coverage. If oil accumulates in the spark plug wells, it can damage the ignition coils and cause misfires. Gasket kits including cam seals and spark plug tube seals cost around €100-150. Labor is 3-5 hours per side.