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Audi · Known Issues

2013 Audi S6 Problems: 4 Known Issues

2013 model year · 294+ owner reports · Updated September 2026

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Issue summary

According to Au7o's analysis of 294+ owner reports, the 2013 Audi S6 has 4 documented known issues. None of the listed issues is rated critical; this is not a complete reliability assessment. The most commonly reported issue is 4.0T Direct Injection Carbon Buildup with 294 owner reports. Across all issues with published estimates, repair costs range from $600 to $1,400. DIY maintenance guides at au7o.io.

In This Article

  • S6 Engine2
  • S6 Cooling1
  • S6 Suspension1
  • Recalls11
  • FAQ
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In This Article

  • Engine2
  • Cooling1
  • Suspension1
  • Recalls11
  • FAQ

All 4 Known Issues

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Community reported
294 owners

On the 2013-2024 Audi S6 4.0T, the S6 4.0T twin-turbo V8 develops carbon deposits on all eight intake valves. The twin-turbo layout and high heat make carbon accumulation aggressive, with symptoms appearing as early as 30,000 miles.

This issue also affects: Audi RS7, Audi S7, Audi S8

Common Symptoms

  • Rough idle
  • Misfires
  • Power loss
  • Hesitation at low RPM
  • Check engine light
  • Uneven cylinder performance

How to Fix

Walnut blast all eight intake runners. Dual-injection models (2019+) are less affected.

Typical repair cost:$600 - $1,400

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Based on 294 owner reports

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Community Reported
High Confidence294 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026

On the 2013-2018 Audi S6 4.0T, the Audi S6 C7 with the 4.0T twin-turbo V8 (direct injection) develops carbon buildup on the intake valves since fuel does not wash over them. This reduces airflow and causes misfires, rough idle, and power loss over time.

This issue also affects: Audi RS7, Audi S7, Audi S8

Common Symptoms

  • Rough idle
  • Misfires at idle
  • Power loss
  • Poor fuel economy
  • Hesitation on acceleration

How to Fix

Confirm carbon buildup by scanning for misfire faults (commonly random/multiple or cylinder-specific misfires), reviewing fuel trims, and inspecting the intake valves with a borescope after removing the intake manifold or accessing the ports. The proper repair is an intake valve carbon cleaning, typically walnut shell blasting each intake port with the valves closed, then replacing intake manifold gaskets, injector seals/O-rings or any disturbed PCV-related seals as needed and clearing/adapting the ECU afterward. If buildup is severe or returns quickly, inspect the PCV/oil separator system and crankcase ventilation hoses for excessive oil carryover. Independent shops typically charge about $800-$1,500 for a full walnut blast service on the 4.0T, while dealer pricing can run roughly $1,500-$2,500 depending on labor and gasket/seal replacement.

Typical repair cost:$600 - $1,200

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Community Reported
Medium Confidence

On the 2013 Audi S6 4.0T, audi TSB 2036167/2 documents slow coolant loss at the turbocharger coolant feed and return connections on 2013 S6 4.0T vehicles in VIN range 000001-127113. Supported signs are a low-coolant warning, a low reservoir level and black encrusted coolant residue at the connections. It does not establish cracking, rapid coolant loss or a six-generation S6 defect.

This issue also affects: Audi RS7, Audi S8, Audi A8

Common Symptoms

  • Low-coolant warning
  • Coolant level below specification
  • Black encrusted residue at turbocharger coolant connections

How to Fix

Confirm the leak source and VIN applicability before ordering parts. For the TSB condition, Audi specifies replacing the coolant feed and return pipes on both cylinder banks, replacing the disturbed oil-feed-pipe O-rings, then refilling and bleeding the cooling system. Service Action 21F7 was VIN-specific and expired in 2019, so current coverage must not be assumed. Do not order the former single pipe or alleged silicone-line kit from this card.

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Manually Verified
High ConfidenceVerifiedReviewed Jul 2026

On the 2013 Audi S6 4.0T, audi TSB 2018765/8 covers 2013 C7 S6 vehicles with air suspension when ride-height adjustment is unavailable, the compressor continues running after shutdown and locking, or the system lowers the car and displays a warning. The bulletin identifies a compressor or J403 relay diagnostic path; it does not establish a universal leaking-strut or valve-block defect.

This issue also affects: Audi RS7, Audi S8, Audi A8

Common Symptoms

  • Self-leveling adjustment is unavailable in the MMI
  • Air-suspension compressor continues after shutdown and locking
  • Vehicle is lowered to its lowest position
  • Air-suspension warning light

How to Fix

Have an Audi-qualified technician test the air-suspension compressor and inspect relay J403. Audi directs replacement of both the compressor and relay when the relay has severe contact erosion or an overheated strand; when the compressor sounds normal and the relay has only minor contact marks, replace the relay only. A sagging corner or leak-down condition requires separate leak localization before any strut is replaced. Do not order the former strut or compressor recommendations from this card.

Research This Issue

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Manually Verified
High ConfidenceVerifiedReviewed Jul 2026
NHTSA Recalls11 recalls

BACK OVER PREVENTION: SENSING SYSTEM: CAMERA

Volkswagen Group of America, Inc. (Audi) is recalling certain 2019-2026 vehicles. Please see the recall report for a complete list of models. A software error may prevent the rearview camera image from displaying as intended. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 111, "Rear Visibility."

Campaign #25V90000019/12/2025

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."

Campaign #21V60600005/08/2021

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Frequently Asked Questions

What are the most common Audi S6 problems?

According to Au7o's analysis of 294+ owner reports, the 2013 Audi S6 has 4 documented issues. The most frequently reported are: 4.0T Direct Injection Carbon Buildup, 2013 Audi S6 Turbocharger Coolant-Pipe Seepage - Diagnosis Required, 2013 Audi S6 Air-Suspension Compressor or Relay Fault - Diagnosis Required. None are rated critical, but regular maintenance is recommended.

Is the Audi S6 reliable?

The 2013 Audi S6 has 4 known issues documented across 294+ owner reports. None of the matching records is rated critical; this is not a complete reliability assessment. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Audi S6 problems?

Repair costs for known Audi S6 issues range from $600 to $1,400, 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 is the 2013-2024 Audi S6 4.0T Direct Injection Carbon Buildup?

The S6 4.0T twin-turbo V8 develops carbon deposits on all eight intake valves. The twin-turbo layout and high heat make carbon accumulation aggressive, with symptoms appearing as early as 30,000 miles. Repairs typically run $600-$1,400. Severity: medium.

What is the 2013 Audi S6 2013 Audi S6 Turbocharger Coolant-Pipe Seepage - Diagnosis Required?

Audi TSB 2036167/2 documents slow coolant loss at the turbocharger coolant feed and return connections on 2013 S6 4.0T vehicles in VIN range 000001-127113. Supported signs are a low-coolant warning, a low reservoir level and black encrusted coolant residue at the connections. It… Severity: medium.

What is the 2013 Audi S6 2013 Audi S6 Air-Suspension Compressor or Relay Fault - Diagnosis Required?

Audi TSB 2018765/8 covers 2013 C7 S6 vehicles with air suspension when ride-height adjustment is unavailable, the compressor continues running after shutdown and locking, or the system lowers the car and displays a warning. The bulletin identifies a compressor or J403 relay diagn… 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.

Data sourced from 294+ owner reports, NHTSA recalls, TSBs, and automotive forums.

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.

Campaign #22V03400026/01/2022

AIR BAGS

Volkswagen Group of America, Inc. (Audi) is recalling certain 2021 Audi RS6 Avant, RS7, 2020-2021 A6 Allroad, S6 Sedan, S7, 2019-2021 A6 Sedan, and A7 vehicles. The score line on the passenger air bag may not have been manufactured correctly.

Campaign #21V15900010/03/2021

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.

Campaign #21V29500026/04/2021

+ 6 more recalls. Check all on NHTSA.gov

Enter your VIN at NHTSA.gov to check recalls specific to your vehicle.

What is the 2013-2018 Audi S6 4.0T Carbon Buildup on Intake Valves?

The Audi S6 C7 with the 4.0T twin-turbo V8 (direct injection) develops carbon buildup on the intake valves since fuel does not wash over them. This reduces airflow and causes misfires, rough idle, and power loss over time. Repairs typically run $600-$1,200. Severity: medium.