The B8.5 S4 with the 3.0T supercharged V6 is generally more reliable than its V8 predecessor, but carbon buildup and specific mechanical failures can turn expensive fast. The DSG transmission is robust, but supporting components wear predictably.
Intake Valve Carbon Buildup
Common · medium severity
Typical onset: 40,000-80,000 mi
Symptoms: Rough idle, especially when cold, Misfires under light load or acceleration, Loss of power and fuel economy, Check engine light with misfire codes (P0300-P0306)
Fix: Walnut blasting both cylinder heads requires intake manifold removal. 4-6 hours labor. Direct injection engines have no fuel wash on intake valves, so carbon accumulates. Catch can installation helps prevent recurrence.
Estimated cost: $600-1,200
Timing Chain Tensioner and Guide Failure
Occasional · high severity
Typical onset: 80,000-120,000 mi
Symptoms: Rattling noise from front of engine on cold start that fades after 5-10 seconds, Metallic ticking that worsens over time, Check engine light with cam/crank correlation codes, Catastrophic engine damage if chain jumps timing
Fix: Full timing service includes tensioners, guides, and chain. Engine-front work requires bumper and accessory removal. 12-16 hours labor. If caught early, prevents internal engine damage. Delayed repairs often result in bent valves or piston contact requiring head work or complete engine rebuild.
Estimated cost: $2,500-4,000
Supercharger Clutch Bearing Failure
Occasional · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: Whining or squealing noise that increases with RPM, Noise present even when not under boost, Loss of boost pressure in advanced stages, Potential for seized supercharger if ignored
Fix: Supercharger must be removed and rebuilt or replaced. Clutch pack and bearings are the common culprits. 8-12 hours labor. Many shops opt for remanufactured unit exchange.
Estimated cost: $2,000-3,500
DSG Transmission Mechatronic Unit Failure
Occasional · high severity
Typical onset: 70,000-120,000 mi
Symptoms: Harsh or delayed shifts, especially 2nd to 3rd gear, Transmission fault warning on dash, Inability to select gears or stuck in one gear, Clunking when shifting between drive and reverse
Fix: Mechatronic unit (valve body with integrated electronics) requires transmission removal or significant drop. 10-14 hours labor. Software updates sometimes help early symptoms, but hardware failure requires unit replacement or rebuild. Fluid and filter service doesn't fix this but may delay onset.
Estimated cost: $3,500-6,000
Transmission Cooler and Mount Leaks
Common · low severity
Typical onset: 60,000-100,000 mi
Symptoms: Transmission fluid drips or puddles under vehicle, Fluid visible on transmission housing or cooler lines, Low fluid warnings if leak is significant, Clunking from worn transmission mount during acceleration/deceleration
Fix: Transmission oil cooler lines and seals fail from heat cycling. Transmission mount (dogbone) wears and causes excessive drivetrain movement. Cooler replacement 3-4 hours, mount replacement 1-2 hours. Often done together during inspection.
Symptoms: Coolant smell or visible leak near front of engine, Low coolant warning light, Overheating if leak progresses, Coolant residue on engine bay components
Fix: Plastic thermostat housing and water pump both known to crack or leak from seals. Front-mounted water pump requires accessory removal. 4-6 hours labor for both together. Always replace as a pair with fresh coolant.
Estimated cost: $800-1,400
PCV System and Oil Consumption Issues
Occasional · medium severity
Typical onset: 50,000-100,000 mi
Symptoms: Excessive oil consumption (1 quart per 1,000-2,000 miles), Blue smoke from exhaust on startup or hard acceleration, Oil pooling in intercooler or intake piping, Rough idle with oil-fouled spark plugs
Fix: Failed PCV valve allows oil vapor into intake. Replace valve cover with integrated PCV, check for intake contamination. 3-4 hours labor. True piston ring wear rare on these engines but documented; if consumption continues after PCV fix, may require engine teardown to inspect rings and cylinder walls. Ring job or short block runs 20-30 hours labor.
Change DSG fluid every 40,000 miles regardless of what Audi says—$300-400 job that saves transmissions
Install an oil catch can around 30,000 miles to minimize carbon buildup on intake valves
Use quality 5W-40 synthetic oil and change every 5,000-7,000 miles, especially if tuned
Listen for timing chain rattle on cold starts—address immediately to avoid $8,000+ engine rebuilds
Budget $1,500-2,000 annually for maintenance beyond consumables if buying over 60,000 miles
Solid performance value if well-maintained with records, but walk away from neglected examples or those with timing rattle—repairs exceed vehicle value quickly.
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 battery required for start-stop system; located under rear cargo floor
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Every control module on the 2013-2017 Audi S4 — 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.
⚠️ Separate modules for driver and passenger if equipped. Basic adaptation only.
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.
Volkswagen Group of America, Inc. (Volkswagen) is recalling certain model year 2013-2015 Audi A4 and S4 vehicles manufactured February 16, 2012, to October 21, 2014, and 2013-2015 Audi Allroad vehicles manufactured March 12, 2012, to October 21, 2014. Due to an improper algorithm in the air bag control module, if a crash necessitates deployment of the side air bags, a second impact to the front of the vehicle may not command the front air bags to also deploy.
Consequence: If the front air bags do not deploy in the event of a secondary impact to the front of the vehicle, there is an increased risk of occupant injury.
Remedy: Volkswagen will notify owners, and Audi dealers will update the air bag control unit software, free of charge. The recall began on November 14, 2014. Owners may contact Audi customer service at 1-800-822-2834. Volkswagen's number for this recall is 69K5.
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 2013 Audi S4 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.