2001 Audi S4 Problems: 4 Known Issues
2001 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 2001 Audi S4 has 4 documented known issues, with 3 rated critical. The most serious are 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines ($2,500-$7,000 repair), 2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go ($1,100-$2,000 repair) and Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ). Across all issues with published estimates, repair costs range from $800 to $7,000. DIY maintenance guides at au7o.io.
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All 4 Known Issues
NHTSA Recalls1 recall
AIR BAGS:FRONTAL:DRIVER SIDE:INFLATOR MODULE
Volkswagen Group of America, Inc. (Volkswagen) is recalling certain 2000-2001 Audi TT Coupe, TT Roadster, 2000-2002 A4, and S4 vehicles equipped with Non-Azide Driver Air Bag Inflators (NADI) that do not contain phase stabilized ammonium nitrate (PSAN) propellant. Due to a manufacturing issue, the NADI inflators may absorb moisture, possibly causing the air bag to deploy improperly in the event of a crash.
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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 2001 Audi S4 has 4 documented issues. The most frequently reported are: 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines, 2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go, Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ). Of these, 3 are rated critical and should be addressed promptly.
Is the Audi S4 reliable?
The 2001 Audi S4 has 4 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 3 issues are rated critical: 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines and 2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go and Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ). 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 $800 to $7,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines, typically costs $2,500-$7,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
What is the 2000-2002 Audi S4 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines?
On the B5 S4's 2.7L twin-turbo V6 (APB/AGB), the turbocharger oil feed and return lines are too small in diameter to move enough oil through the turbo bearing housings. After a hot shutdown the residual oil bakes (cokes) inside the lines, progressively restricting flow until the… Repairs typically run $2,500-$7,000. Severity: high.
What is the 2000-2002 Audi S4 2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go?
Unlike every later S4, the B5's 2.7T 30V V6 uses a TIMING BELT, and it is an interference design. A snapped belt, a seized tensioner/idler, or a water pump that fails and shreds the belt results in bent valves and, in some cases, cracked pistons - a total engine rebuild. The revi… Repairs typically run $1,100-$2,000. Severity: high.
What is the 2000-2002 Audi S4 Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ)?
Certain 2000-2002 S4 vehicles have a non-azide driver airbag inflator that can absorb moisture and deploy improperly, reducing occupant protection in a crash. Severity: high.
What is the 2000-2002 Audi S4 B5 Front Multi-Link Control Arm Bushings and Ball Joints Wear Out, Causing Clunks and Wandering Steering?
The B5 S4 uses a multi-link front suspension with four control arms per side, and both the rubber bushings and the integrated ball joints are known short-life items - a problem noted even on relatively fresh cars and now universal given the fleet's age. The rubber compound harden… Repairs typically run $800-$2,000. 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.