The B7 S4 with its 4.2L V8 is a sublime driver's car when healthy, but the timing chain guides and carbon buildup issues make it a ticking time bomb that demands proactive maintenance and deep pockets.
Timing Chain Guide and Tensioner Failure
Common · high severity
Typical onset: 60,000-100,000 mi
Symptoms: Cold-start rattle lasting 2-5 seconds that progressively worsens, Metallic chain slap from front of engine, Check engine light with cam/crank correlation codes, Catastrophic engine damage if chains jump timing
Fix: Engine-out service requiring full timing system replacement including all guides, tensioners, and chains. 20-25 labor hours. This is THE major service interval item that separates good from grenaded engines.
Estimated cost: $4,500-7,000
Carbon Buildup on Intake Valves
Common · medium severity
Typical onset: 50,000-80,000 mi
Symptoms: Rough idle and misfires especially when cold, Loss of power and throttle response, Poor fuel economy, Multiple misfire codes across cylinders
Fix: Direct-injection FSI engine with no fuel washing valves. Requires walnut blasting media through intake ports with manifolds removed. 6-8 hours labor. Should be done preventively every 60k-80k.
Estimated cost: $800-1,200
Oil Consumption and Piston Ring Failure
Occasional · high severity
Typical onset: 80,000-120,000 mi
Symptoms: Burning 1+ quart per 1,000 miles, Blue smoke on startup or acceleration, Fouled spark plugs, Low compression readings on multiple cylinders
Fix: Piston ring lands crack or rings fail due to carbon buildup and heat cycling. Only real fix is engine rebuild or short block replacement. 30-40 hours labor. Some early engines eligible for Audi warranty extension.
Estimated cost: $12,000-18,000
Transmission Control Unit and Mechatronic Failures
Occasional · high severity
Typical onset: 70,000-110,000 mi
Symptoms: Harsh or delayed shifts, Stuck in gear or limp mode, Clunking into gear from stop, Check engine light with transmission fault codes
Fix: The 6-speed automatic's mechatronic unit and TCU are failure-prone. Rebuild or replacement requires transmission drop. 8-12 hours labor. Remanufactured units available.
Estimated cost: $2,500-4,500
Control Arm Bushings and Front Suspension Wear
Common · low severity
Typical onset: 60,000-90,000 mi
Symptoms: Clunking over bumps, Wandering steering or poor tracking, Uneven tire wear, Alignment won't hold
Fix: Multiple control arms with pressed bushings wear out. Best practice is replacing complete arms rather than pressing bushings. 4-6 hours for full front refresh including alignment.
Estimated cost: $1,200-2,000
Rear Differential and Transmission Mounts
Common · low severity
Typical onset: 70,000-100,000 mi
Symptoms: Clunk on acceleration or deceleration, Vibration at highway speeds, Excessive driveline movement felt through shifter
Fix: Mounts crack and tear from V8 torque and Quattro drivetrain stress. Straightforward replacement. 2-3 hours labor for trans mount, 1.5-2 hours for rear diff mount.
Estimated cost: $400-800
Fuel Pump Controller and High-Pressure Pump Issues
Occasional · medium severity
Typical onset: 80,000-120,000 mi
Symptoms: No-start or extended crank time, Stumbling under acceleration, Limp mode with fuel system codes, Fuel pressure below spec
Fix: FSI direct injection uses both in-tank pump and engine-driven high-pressure pump. Controller module under rear seat fails from heat. 2-4 hours depending on which component.
Estimated cost: $800-1,800
Owner tips
Budget $1,500-2,000/year for maintenance beyond consumables if you're past 70k miles
Do timing chains BEFORE you hear rattling — by then damage may already be occurring
Run high-quality 5W-40 synthetic oil and change every 5,000 miles maximum to combat carbon and ring issues
Get a pre-purchase inspection with compression test and borescope inspection if buying used
Walnut blast the intake valves every 60k-70k as preventive maintenance, not when misfires start
Buy one only if timing chains are documented done or you have $5k-7k ready to do them immediately — otherwise you're gambling with a grenade.
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: Located in trunk on passenger side; AGM battery required for electronic systems
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Control Modules — 2008 Audi S4
Every control module on the 2008-2012 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.
AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE · 18V427000
2018-06-22 · EA15001
Volkswagen Group of America, Inc. (Volkswagen) is recalling certain 2005-2008 Audi A4 Sedan, A4 Avant, S4 Avant and S4 Sedan, 2007-2008 RS4 Sedan, 2004 RS4 Cabriolet, 2007-2009 A4 Cabriolet and S4 Cabriolet, 2005-2011 A6 Sedan, 2006-2011 A6 Avant, and 2007-2011 S6 Sedan vehicles. These vehicles are equipped with certain air bag inflators assembled as part of the passenger frontal air bag modules used as original equipment or replacement equipment. In the event of a crash necessitating deployment of the passenger frontal air bag, these inflators may explode due to propellant degradation occurring after long-term exposure to absolute humidity and temperature cycling.
Consequence: An inflator explosion may result in sharp metal fragments striking the driver or other occupants resulting in serious injury or death.
Remedy: Audi has notified owners, and dealers will replace the passenger frontal air bag with an alternate remedy part, free of charge. The recall began June 29, 2018. Owners may contact Audi customer service at 1-800-253-2834. Volkswagen's number for this recall is 69R7. Note: This recall supersedes recalls 16V382, 17V032 and 18V004 and includes vehicles that may have had their air bag previously replaced under one of those campaigns.
AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE · 17V032000
2017-01-11 · EA15001
Volkswagen Group of America, Inc. (Volkswagen) is recalling certain 2009 Audi A4 Cabriolet, S4 Cabriolet, A6 Avant, A6 Sedan and S6 Sedan vehicles originally sold, or ever registered, in Arizona, Arkansas, Delaware, the District of Columbia, Illinois, Indiana, Kansas, Kentucky, Maryland, Missouri, Nebraska, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, and West Virginia, or "Zone B."
Additionally, unless included in "Zone B" above, Volkswagen is recalling certain 2005-2008 Audi A4 Avant, A4 Sedan, A6 Sedan, S4 Avant and S4 Sedan vehicles, 2007-2008 A4 Cabriolet, RS4 Sedan, S4 Cabriolet and S6 Sedan vehicles, and 2006-2008 A6 Avant and 2008 RS4 Cabriolet vehicles originally sold, or ever registered, in Alaska, Colorado, Connecticut, Idaho, Iowa, Maine, Massachusetts, Michigan, Minnesota, Montana, New Hampshire, New York, North Dakota, Oregon, Rhode Island, South Dakota, Utah, Vermont, Washington, Wisconsin, and Wyoming.
These vehicles are equipped with certain air bag inflators assembled as part of the passenger frontal air bag modules used as original equipment or replacement equipment. In the event of a crash necessitating deployment of the front air bags, these inflators may rupture due to propellant degradation occurring after long-term exposure to absolute humidity and temperature cycling.
Consequence: An inflator rupture may result in metal fragments striking the vehicle occupants resulting in serious injury or death.
Remedy: Audi will notify owners, and dealers will replace the passenger frontal air bag inflator, free of charge. The recall began March 30, 2018. Owners may contact Audi customer service at 1-800-253-2834. Note: This recall has been superseded by recall number 18V427.
Vehicle Info — 2008 Audi S4
Performance
Horsepower
340hp
Torque
302lb-ft
0–60 mph
5.0sec
Quarter mile
13.5sec
Top speed
155mph
Capability & size
Curb weight
4,079lb
Wiper blades
B7 generation sedan. Some sources show 22/19 configuration.
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 2008 Audi S4 4.2L V8 and can vary by trim.
🔧 Built by master technician Chris Hackleman · Master Technician · 20+ years.