What is the 2011-2012 Audi S4 Fuel Rail or Seal Leak Creates Fire Risk (Recall 15V019 / 24AP)?

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.

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 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 2005-2009 Audi S4 Passenger Airbag Inflator Can Rupture (Recall 18V427 / 69R7)?

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.

What is the 2010-2025 Audi S4 Thermostat Housing Failure and Coolant Leak?

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.

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.

What is the 2010-2016 Audi S4 Carbon Deposits Build Up on the Intake Valves of the Direct-Injected 3.0 TFSI?

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.

What is the 2010-2016 Audi S4 3.0 TFSI PCV / Air-Oil Separator Diaphragm Ruptures, Causing Oil Consumption and a Crankcase Vacuum Leak?

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.

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 2010-2016 Audi S4 Supercharger Coupler (Isolator) Wears Out and Rattles Like a Bag of Marbles?

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.

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.

Audi · Known Issues

2000-2025 Audi S4 Problems: 19 Known Issues

2000-2025 model years · 107+ owner reports · Updated August 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), 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), EA839 3.0T Water Pump Internal Seal Failure Leaks Coolant Into the Vacuum System (Class Action). at .

Frequently Asked Questions

What are the most common Audi S4 problems?

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.

Is the Audi S4 reliable?

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 4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair) 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. 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 $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.

What year Audi S4 is the most reliable?

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.

All 19 Known Issues

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Frequently Asked Questions

What are the most common Audi S4 problems?

Is the Audi S4 reliable?

How much does it cost to fix common Audi S4 problems?

What year Audi S4 is the most reliable?

Airbag-Control Software May Miss Front-Airbag Deployment After a Second Impact (Recall 14V667 / 69K5)#

Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ)#

Passenger Airbag Inflator Can Rupture (Recall 18V427 / 69R7)#

Seat-Heater Cable Contact Fault Disables the Passenger Airbag (Recall 21V874 / 74E3)#

2.7T Timing Belt Service Is Mandatory - Interference Engine Destroys Itself if the Belt or Tensioner Lets Go#

4.2 V8 Timing Chain Guides, Tensioners and Cam Adjusters Fail at the Rear of the Engine (Engine-Out Repair)#

2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines#

Carbon Deposits Build Up on the Intake Valves of the Direct-Injected 3.0 TFSI#

3.0 TFSI PCV / Air-Oil Separator Diaphragm Ruptures, Causing Oil Consumption and a Crankcase Vacuum Leak#

Supercharger Coupler (Isolator) Wears Out and Rattles Like a Bag of Marbles#

EA839 3.0T Water Pump Internal Seal Failure Leaks Coolant Into the Vacuum System (Class Action)#

Thermostat Housing Failure and Coolant Leak#

0B5 DL501 S tronic Mechatronic Unit Failure - Harsh Shifts, Erratic Gear Selection and Limp Mode#

Dual-Mass Flywheel Springs Break on the 6-Speed Manual 4.2 V8#

Rear Axle Trailing Arm Eccentric Bolt Lock Nut Can Break from Stress Corrosion (Recall 21V295 / 42L1)#

B5 Front Multi-Link Control Arm Bushings and Ball Joints Wear Out, Causing Clunks and Wandering Steering#

Fuel Rail or Seal Leak Creates Fire Risk (Recall 15V019 / 24AP)#

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#

What is the 2013-2015 Audi S4 Airbag-Control Software May Miss Front-Airbag Deployment After a Second Impact (Recall 14V667 / 69K5)?

What is the 2011-2012 Audi S4 Fuel Rail or Seal Leak Creates Fire Risk (Recall 15V019 / 24AP)?

What is the 2000-2002 Audi S4 Driver Airbag Inflator May Deploy Improperly (Recall 21V470 / 69CJ)?

What is the 2003-2004 Audi S4 Xenon Headlamp Reflector Coating Can Reduce Light Output (Recall 05V096)?

What is the 2005-2009 Audi S4 Passenger Airbag Inflator Can Rupture (Recall 18V427 / 69R7)?

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?

What is the 2018-2020 Audi S4 Seat-Heater Cable Contact Fault Disables the Passenger Airbag (Recall 21V874 / 74E3)?

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)?

What is the 2018-2025 Audi S4 EA839 3.0T Water Pump Internal Seal Failure Leaks Coolant Into the Vacuum System (Class Action)?

What is the 2010-2016 Audi S4 0B5 DL501 S tronic Mechatronic Unit Failure - Harsh Shifts, Erratic Gear Selection and Limp Mode?

What is the 2020-2021 Audi S4 Rear Axle Trailing Arm Eccentric Bolt Lock Nut Can Break from Stress Corrosion (Recall 21V295 / 42L1)?

What is the 2000-2002 Audi S4 2.7T Biturbo Turbocharger Failure from Undersized, Coking Oil Feed and Return Lines?