2004 Audi S4 Problems: 4 Known Issues
2004 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated October 2026
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2004 Audi S4 has 4 documented known issues, with 2 rated critical. The most serious are 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair) ($4,500-$10,000 repair) and Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096). Across all issues with published estimates, repair costs range from $500 to $10,000. DIY maintenance guides at au7o.io.
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All 4 Known Issues
NHTSA Recalls3 recalls
AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE
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.
AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE
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.
EXTERIOR LIGHTING:HEADLIGHTS
ON CERTAIN PASSENGER VEHICLES, THERE IS A POSSIBILITY OF XENON HEADLAMP COATING DEGRADATION OVER TIME. THE LUMINOUS TRANSMITTANCE OF THE HEADLAMP MAY DECREASE OVER A PERIOD OF TIME.
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Frequently Asked Questions
What are the most common Audi S4 problems?
According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2004 Audi S4 has 4 documented issues. The most frequently reported are: 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair), Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096), Secondary Air Injection System Faults - Failed Pump, Stuck Combi Valves and Carbon-Clogged Head Passages. Of these, 2 are rated critical and should be addressed promptly.
Is the Audi S4 reliable?
The 2004 Audi S4 has 4 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 2 issues are rated critical: 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair) and Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
How much does it cost to fix common Audi S4 problems?
Repair costs for known Audi S4 issues range from $500 to $10,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair), typically costs $4,500-$10,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 2004-2008 Audi S4 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair)?
The B6/B7 S4's 4.2L V8 (BBK/BHF) drives its timing chains from the BACK of the engine, against the firewall. What owners call "timing chain failure" is really the plastic chain guides, the chain tensioners and the two camshaft adjusters wearing out and disintegrating. Forum docum… Repairs typically run $4,500-$10,000. Severity: high.
What is the 2003-2004 Audi S4 Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096)?
Certain 2003-2004 S4 xenon headlamp reflectors can lose coating over time, reducing luminous transmittance and the driver’s field of view. Severity: high.
What is the 2004-2008 Audi S4 Secondary Air Injection System Faults - Failed Pump, Stuck Combi Valves and Carbon-Clogged Head Passages?
The secondary air injection (SAI) system pumps air into the exhaust ports on cold start to light off the catalysts, and it is a chronic check-engine-light source on these cars. Each bank has its own combi valve. Carbon causes the combi valve to stick open, which lets hot, moist e… Repairs typically run $500-$2,000. Severity: medium.
What is the 2004-2008 Audi S4 Dual-Mass Flywheel Springs Break on the 6-Speed Manual 4.2 V8?
Manual-transmission B6 and B7 S4s use a dual-mass flywheel behind the 4.2 V8, and the internal damper springs fail. The failure is progressive and intermittent early on - owners describe shudder and vibration that appear for days, vanish, then come back and stay - before settling… Repairs typically run $1,800-$4,000. Severity: medium.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.