2014 AUDI RS5

Typical onset: 60,000-100,000 mi

Symptoms: rough idle and misfires, loss of power especially under load, check engine light with multiple misfire codes, valve lifter noise or ticking, complete loss of compression in one or more cylinders

Fix: The direct-injection 4.2 FSI accumulates carbon on intake valves with no fuel wash. If neglected past 80k, carbon chunks break off and score cylinder walls or lodge under valves causing bent valves, damaged pistons, and scored bores. Preventive walnut blasting every 40-50k miles takes 4-6 hours. Once damage occurs, you're looking at engine-out work: piston replacement, cylinder honing or sleeving, head work, potentially full short block. Complete rebuild runs 40-60 shop hours.

Estimated cost: $800-1,200 preventive (walnut blasting) / $12,000-22,000 engine rebuild

Typical onset: 70,000-110,000 mi

Symptoms: transmission slipping or harsh shifts, milky transmission fluid (coolant contamination), overheating transmission temp warnings, coolant loss with no external leaks

Fix: The S-tronic dual-clutch transmission cooler can develop internal leaks allowing coolant and ATF to cross-contaminate. This destroys the transmission if driven after contamination starts. Requires cooler replacement, complete fluid flush of both systems, and often transmission replacement if caught late. Cooler alone is 3-4 hours, but if the trans is cooked you're at 12-16 hours for R&R and mechatronic replacement.

Estimated cost: $1,200-2,000 cooler only / $8,000-12,000 with transmission damage

Typical onset: 50,000-90,000 mi

Symptoms: clunking when shifting from P to D or D to R, excessive driveline vibration under acceleration, visible movement of transmission when engine is revved in park

Fix: The factory hydraulic transmission mounts fail from the aggressive shifts and high torque. Driven hard, they collapse even sooner. Front and rear trans mounts should be replaced as a pair. 2-3 hours labor with subframe partially dropped for access.

Estimated cost: $800-1,400

Typical onset: 80,000-120,000 mi

Symptoms: extended cranking before start especially when hot, stumbling or hesitation under hard acceleration, fuel trims way out of spec, high-pressure fuel system fault codes

Fix: The in-tank fuel filter isn't a regular service item in Audi's eyes, but it clogs over time, starving the high-pressure pump. This causes pump wear and eventual failure. Filter replacement requires tank drop (3-4 hours). If the pump is damaged, add another 2 hours and significant parts cost. Do the filter proactively at 60-80k if you plan to keep the car.

Estimated cost: $600-1,000 filter / $1,800-2,800 with pump

Typical onset: 100,000+ mi or with poor oil service history

Symptoms: knocking noise from lower engine especially on cold start, metallic rattling that worsens with RPM, low oil pressure warnings, metal debris in oil during changes

Fix: The FSI V8 has tight bearing tolerances and demands quality oil and 5,000-mile intervals maximum. Missed changes or running low on oil accelerates bearing wear. Once knocking starts, it's too late—you need a full rotating assembly rebuild with crank polishing or replacement, new bearings, and often pistons. Engine-out, full teardown: 50+ hours.

Estimated cost: $15,000-25,000