The 2017 Audi S5 with the 3.0T supercharged V6 is generally reliable but shares critical weak points with the B8.5 platform, particularly catastrophic timing chain failures and transmission cooling issues that can lead to expensive repairs if neglected.
Timing Chain Tensioner Failure Leading to Engine Carnage
Occasional · high severity
Typical onset: 80,000-140,000 mi
Symptoms: Cold-start rattle lasting 2-5 seconds that progressively worsens, Check engine light with timing correlation codes (P000A, P000B), Catastrophic failure: sudden loss of power, violent mechanical noise, no restart
Fix: If caught early with just rattle, timing chain service runs 12-16 hours labor. If tensioner fails completely, chain jumps timing and valves contact pistons—requires full engine rebuild or replacement. Early intervention is critical.
Transmission Oil Cooler Line Leaks and Cooler Failure
Common · high severity
Typical onset: 60,000-100,000 mi
Symptoms: Transmission fluid spots under vehicle, often pink/red, Harsh shifting or slipping when transmission overheats, Low transmission fluid warning on cluster, In severe cases, coolant mixing with ATF causing milky fluid
Fix: Factory cooler lines crack at crimp points; cooler itself can internally leak mixing coolant and ATF. Replace lines and cooler together (8-10 hours). If contamination occurred, full flush and possible valve body replacement needed.
Estimated cost: $1,800-3,200 for lines/cooler, $4,000-6,500 if contamination damage
Carbon Buildup on Intake Valves
Common · medium severity
Typical onset: 50,000-80,000 mi
Symptoms: Rough idle and misfires at cold start, Loss of power and throttle response, especially under 3,000 RPM, Increased fuel consumption, Multiple cylinder misfire codes (P0300-P0306)
Fix: Direct injection engines with no port injection suffer heavy valve carbon deposits. Requires walnut blasting media cleaning—supercharger removal for access adds complexity. 6-8 hours labor. Should be done every 50-60k miles as preventive maintenance.
Estimated cost: $800-1,400
Transmission Mounts Deteriorating
Common · low severity
Typical onset: 70,000-110,000 mi
Symptoms: Clunking when shifting from Park to Drive or Reverse, Vibration through chassis at idle in Drive, Excessive drivetrain movement visible during acceleration, Transmission appears to sag when inspected on lift
Fix: Hydraulic transmission mounts fail from age and stress. Front mount most common, but recommend replacing all mounts simultaneously. 3-4 hours labor with subframe support required.
Estimated cost: $600-1,100
Water Pump and Thermostat Housing Leaks
Occasional · medium severity
Typical onset: 80,000-120,000 mi
Symptoms: Coolant smell in cabin or under hood, Visible coolant weeping from front of engine, Low coolant warning light, Overheating in severe cases if leak progresses
Fix: Plastic thermostat housing and water pump develop leaks at gasket surfaces or crack from heat cycles. Replace both together with updated parts—10-12 hours with supercharger removal for proper access. Don't chase individual leaks.
Estimated cost: $1,800-2,800
PCV System and Valve Cover Gasket Oil Leaks
Common · low severity
Typical onset: 60,000-100,000 mi
Symptoms: Oil residue on top of engine and around valve covers, Burning oil smell from exhaust heat, Oil consumption between changes (1 qt per 2,000-3,000 mi), Check engine light for intake system leaks (P2279, P2261)
Fix: Valve cover gaskets shrink and PCV diaphragms tear, causing vacuum leaks and oil seepage. Replace gaskets, PCV valve, and pressure regulation valve. 4-5 hours labor. Often done during carbon cleaning.
Estimated cost: $800-1,300
Owner tips
Change oil every 5,000 miles with quality 5W-40 synthetic—short trips and cold starts stress the timing system
Listen for ANY cold-start rattle and address immediately—timing chain failure destroys engines
Check transmission fluid color every oil change; pink/red is good, brown or milky means immediate attention needed
Budget for carbon cleaning every 50-60k miles; it's maintenance not a repair on direct injection
Use Audi-approved transmission fluid only (G055025A2 or equivalent)—wrong fluid accelerates clutch pack wear
Buy one with documented timing chain service under 100k miles and verified clean transmission history; otherwise budget $5k+ immediately for deferred maintenance—the drivetrain grenades when neglected.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: AGM required for start-stop system; battery located in trunk under floor
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Every control module on the 2017-2026 Audi S5 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
⚠️ Optional equipment. Qi wireless charging. Minimal coding typically required.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2017 Audi S5 3.0L Supercharged V6 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.