Audi · Known Issues
2000-2025 Audi S4 Problems: 19 Known Issues
2000-2025 model years · 107+ owner reports · Updated September 2026
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2000-2025 model years · 107+ owner reports · Updated September 2026
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According to Au7o's analysis of 107+ owner reports, the 2000-2025 Audi S4 has 19 documented known issues, with 12 rated critical. The most serious are Airbag-Control Software May Miss Front-Airbag Deployment After a Second Impact (Recall 14V667 / 69K5), Fuel Rail or Seal Leak Creates Fire Risk (Recall 15V019 / 24AP), Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ), Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096), Passenger Airbag Inflator Can Rupture (Recall 18V427 / 69R7), 2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go ($1,100-$2,000 repair), Seat-Heater Cable Contact Fault Disables the Passenger Airbag (Recall 21V874 / 74E3) ($0-$0 repair), EA839 3.0T Water Pump Internal Seal Failure Leaks Coolant Into the Vacuum System (Class Action) ($1,200-$3,000 repair), 0B5 DL501 S tronic Mechatronic Unit Failure - Harsh Shifts, Erratic Gear Selection and Limp Mode ($1,800-$7,000 repair), Rear Axle Trailing Arm Eccentric Bolt Lock Nut Can Break from Stress Corrosion (Recall 21V295 / 42L1) ($0-$0 repair), 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines ($2,500-$7,000 repair) and 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). The most commonly reported issue is Thermostat Housing Failure and Coolant Leak with 107 owner reports. Across all issues with published estimates, repair costs range from $300 to $10,000. DIY maintenance guides at au7o.io.
EQUIPMENT:ELECTRICAL:INFOTAINMENT:VIDEO (TOUCH)SCREEN/MONITOR/UNIT
Volkswagen Group of America, Inc. (Audi) is recalling certain 2021-2022 AUDI A8, A6 Allroad, E-TRON Quattro, 2022 S3, RSQ8, RS7, RS6 Avant, Q8, Q7, Q3, E-TRON Sportback Quattro, S5 Cabriolet, E-TRON GT, S5 Sportback, A7, A6, A5 Sportback, A5 Cabriolet, A4, A4 Allroad, A3, S8, SQ7, SQ8, S6, and S4 vehicles. The infotainment main unit may become damaged internally when the vehicle is shut off, resulting in an inoperative rearview camera display the next time the vehicle is started. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 111, "Rear Visibility."
SEAT BELTS:REAR/OTHER:RETRACTOR
Volkswagen Group of America, Inc. (Volkswagen) is recalling certain 2021 Volkswagen ID4, Audi A4 Allroad, A4 Sedan, A5 Cabriolet, A5 Coupe, A5 Sportback, A6 Allroad, A6 Sedan, A7, A8, E-Tron Quattro, E-Tron Sportback Quattro, Q3, Q5, Q5 Sportback, Q7, Q8, RS5 Sportback, RS5 Coupe, RS6 Avant, RS7, RSQ8, S4 Sedan, S5 Cabriolet, S5 Coupe, S5 Sportback, S6 Sedan, S7, S8, SQ5, SQ5 Sportback, SQ7, SQ8, and 2021-2022 S3 Sedan vehicles. The rear seat belt automatic locking retractors may deactivate early, which can prevent the child restraint system from securing properly. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 208, "Occupant Crash Protection."
TIRES
Volkswagen Group of America, Inc. (Audi) is recalling certain 2019-2021 Audi A5 Sportback, RS5 Coupe, RS5 Sportback, S5 Sportback, 2020-2021 A4 Allroad, A4 Sedan, A5 Cabriolet, A5 Coupe, A6 Allroad, A6 Sedan, A7, A8, Q5, S4 Sedan, S5 Coupe, S5 Cabriolet, S6 Sedan, S7, S8, SQ5, 2021 Q5 Sportback, Q7, Q8, RS6 Avant, RS7, RSQ8, SQ5 Sportback, SQ7, and SQ8 vehicles. The rear axle alignment may not have been inspected after the repairs for Recall 21V-295 (42L1) were performed.
SUSPENSION:REAR:AXLE:NON-POWERED AXLE ASSEMBLY
Volkswagen Group of America, Inc. (Audi) is recalling certain 2021 Q7, Q8, Q5 Sportback, SQ5 Sportback, RS6 Avant, RS7, RS Q8, 2020-2021 Audi S6 sedan, Q5, A8, S8, A7, A6 Allroad, A5 Cabriolet, A4 sedan, A4 Allroad, SQ5, S7, A6 sedan, S5 coupe, S4 sedan, S5 Cabriolet, A5 coupe, 2019-2021 RS5 coupe, A5 Sportback, S5 Sportback, RS5 Sportback vehicles. The lock nut on the trailing arm of the rear axle may break due to stress corrosion.
BACK OVER PREVENTION:DISPLAY FUNCTION
Volkswagen Group of America, Inc. (Volkswagen) is recalling certain 2021 Audi A8, RS7, RS6 Avant, RS5 Sportback, RS5 Coupe, Q8, Q7, Q5 Sportback, S4 Sedan, Q5, A7, A6, A6 Allroad, A5 Sportback, A5 Coupe, A5 Cabrioleet, A4 Sedan, A4 Allroad, E-Tron Sportback Quattro, SQ7, S5 Cabriolet, E-Tron Quattro, SQ8, SQ5 Sportback, SQ5, S8, S7, S6 Sedan, S5 Sportback, S5 Coupe, 2022 E-Tron GT, and 2021-2022 RSQ8 vehicles. Due to a software issue, a blank or black screen may be displayed instead of the rearview camera image when the vehicle is placed in reverse gear. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 111, "Rear Visibility."
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According to Au7o's analysis of 107+ owner reports, the 2000-2025 Audi S4 has 19 documented issues. The most frequently reported are: Airbag-Control Software May Miss Front-Airbag Deployment After a Second Impact (Recall 14V667 / 69K5), Fuel Rail or Seal Leak Creates Fire Risk (Recall 15V019 / 24AP), Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ). Of these, 12 are rated critical and should be addressed promptly.
The 2000-2025 Audi S4 has 19 known issues documented across 107+ owner reports. 12 issues are rated critical: Airbag-Control Software May Miss Front-Airbag Deployment After a Second Impact (Recall 14V667 / 69K5) and Fuel Rail or Seal Leak Creates Fire Risk (Recall 15V019 / 24AP) and Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ) and Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096) and Passenger Airbag Inflator Can Rupture (Recall 18V427 / 69R7) and 2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go and Seat-Heater Cable Contact Fault Disables the Passenger Airbag (Recall 21V874 / 74E3) and EA839 3.0T Water Pump Internal Seal Failure Leaks Coolant Into the Vacuum System (Class Action) and 0B5 DL501 S tronic Mechatronic Unit Failure - Harsh Shifts, Erratic Gear Selection and Limp Mode and Rear Axle Trailing Arm Eccentric Bolt Lock Nut Can Break from Stress Corrosion (Recall 21V295 / 42L1) and 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines and 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair). 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.
Repair costs for known Audi S4 issues range from $0 to $10,000, depending on the specific problem and whether you choose DIY or professional repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
Reliability varies across model years of the Audi S4. Based on documented issues, problems are most commonly reported in earlier model years. Au7o recommends checking the specific known issues for your target year before purchasing, and having a pre-purchase inspection performed by a qualified mechanic. Our known issues database covers the 2000-2025 Audi S4 with 19 documented issues documented across 107+ owner reports.
On certain 2013-2015 S4 vehicles, an airbag-control algorithm may fail to command the front airbags after a side-airbag deployment followed by a second frontal impact. Severity: high.
Certain 2011-2012 S4 fuel-injection systems can leak at the fuel rails or corresponding seals, creating a fire risk near an ignition source. Severity: high.
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.
Certain 2003-2004 S4 xenon headlamp reflectors can lose coating over time, reducing luminous transmittance and the driver’s field of view. Severity: high.
Certain 2005-2009 S4 body styles contain passenger frontal-airbag inflators that can rupture after long-term humidity and temperature exposure, propelling metal fragments into the cabin. Severity: high.
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.
On B9 S4 sedans, the cable connecting the front passenger seat heater to the Passenger Occupant Detection System (PODS) can develop a contact fault. The PODS software reads the fault as a system malfunction and switches the passenger front airbag OFF, so the airbag will not deplo… Repairs typically run $0-$0. Severity: high.
The B9 S4's turbocharged EA839 3.0T uses a water pump whose internal seals fail, and the failure mode is unusual: coolant does not only weep externally, it is drawn INTO the engine's vacuum circuit and other places coolant should never reach, contaminating vacuum lines and compon… Repairs typically run $1,200-$3,000. Severity: high.
S4s ordered with the 7-speed S tronic dual-clutch use the 0B5 (DL501) gearbox, whose mechatronic control unit - the valve body with its integrated solenoids, pressure sensors and TCU - is a documented weak point in high-torque applications like the S4. Failures start as harsh or… Repairs typically run $1,800-$7,000. Severity: high.
Lock nuts from particular production batches used on the eccentric bolt at the rear-axle trailing arm can crack from stress corrosion. If the nut breaks, the eccentric bolt can move and the rear-axle wheel alignment changes - and at higher speed the rear axle can suddenly and unc… Repairs typically run $0-$0. Severity: high.
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.
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.
The plastic thermostat housing on the S4 3.0T is prone to cracking and leaking coolant. The housing sits at the rear of the engine making leaks hard to spot until coolant loss is significant. Repairs typically run $300-$800. Severity: medium.
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.
The B8/B8.5 S4's Eaton TVS roots supercharger drives its rotor pack through a plastic coupler disc between the drive snout and the driven rotor. Over time the drive holes in that plastic coupler elongate and wear, and the slop shows up as a distinct rattling / marbles-in-a-can no… Repairs typically run $400-$1,500. Severity: medium.
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.
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.
The supercharged 3.0 TFSI's crankcase ventilation module (PCV / air-oil separator) uses an internal diaphragm that hardens and tears. When it does, the engine pulls unmetered air through the crankcase, gives up its ability to control crankcase pressure, and starts drawing oil int… Repairs typically run $300-$900. Severity: medium.
The B8/B8.5 S4's 3.0 TFSI is direct-injected: fuel is sprayed into the cylinder rather than over the back of the intake valve, so nothing washes the valve stems clean. Combined with oil vapor routed back through the crankcase ventilation system, hard carbon accumulates on the int… Repairs typically run $500-$1,200. 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.