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Audi · Known Issues

2018 Audi S8 Problems: 7 Known Issues

2018 model year · 823+ owner reports · Updated September 2026

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Issue summary

According to Au7o's analysis of 823+ owner reports, the 2018 Audi S8 has 7 documented known issues, with 4 rated critical. The most serious are Adaptive Air Suspension Multi-Point Failure ($1,200-$4,500 repair), ZF 8-Speed Torque Converter and Valve Body Issues ($2,500-$6,000 repair), 4.0T Turbo Coolant System Degradation ($1,000-$3,500 repair) and Water-to-Air Intercooler Internal Coolant Leak (Coolant into Intake) ($1,500-$3,500 repair). The most commonly reported issue is Adaptive Air Suspension Multi-Point Failure with 292 owner reports. Across all issues with published estimates, repair costs range from $200 to $6,000. DIY maintenance guides at au7o.io.

In This Article

  • S8 Cooling2
  • S8 Suspension1
  • S8 Transmission1
  • S8 Fuel System1
  • S8 Engine1
  • S8 Body/Panels1
  • Recalls10
  • FAQ
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In This Article

  • Cooling2
  • Suspension1
  • Transmission1
  • Fuel System1
  • Engine1
  • Body/Panels1
  • Recalls10
  • FAQ

All 7 Known Issues

Filter:
ALL YEARS20262025202420232022202120202019201820172016201520142013201220112010200920082007200320022001

When Issues Typically Appear

ZF 8-Speed Torque Converter and Valve Body Issues
40K-60K
4.0T Turbo Coolant System Degradation
48K-72K
Adaptive Air Suspension Multi-Point Failure
60K-100K
025K50K75K100K mi
Community reported
243 owners

On the 2013-2024 Audi S8 4.0T, the S8 4.0T V8 shares coolant line issues with other 4.0T Audi models but the heavier sedan and higher power tune accelerate wear. Turbo oil and coolant line failures can cause expensive damage if not caught early.

This issue also affects: Audi A1, Audi A3, Audi A6

Common Symptoms

  • Coolant loss
  • Turbo oil leak smell
  • Overheating warning
  • White exhaust smoke
  • Low coolant light
  • Oil in coolant or coolant in oil

How to Fix

Replace all turbo coolant and oil feed lines preventatively at 60,000 miles. Monitor coolant levels closely.

Typical repair cost:$1,000 - $3,500

Research This Issue

Based on 243 owner reports

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Community Reported
High Confidence243 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026

On the 2013-2018 Audi S8 4.0T TFSI V8 (CTFA/CGTA/CWUC), the 4.0T uses a compact water-to-air charge-air cooler mounted in the hot 'V' between the cylinder banks. The intercooler core can develop an internal leak that allows engine coolant to weep directly into the pressurized intake path. Owners report slow, unexplained coolant loss with no puddle on the ground, sweet-smelling white smoke from the exhaust (worst on cold startup), and in advanced cases milky residue inside the charge piping. If ignored, coolant ingestion can hydro-lock or otherwise damage the engine. Because it sits in the valley, this is a labor-intensive repair distinct from the more common thermostat-housing/water-pump leaks.

This issue also affects: Audi A4, Audi A1, Audi A5

Common Symptoms

  • Unexplained coolant loss with no visible external leak
  • Sweet-smelling white smoke from exhaust, especially on cold startup
  • Milky/creamy residue in intake piping
  • Rough idle or misfire under load

How to Fix

Confirm the source: pressure-test the cooling system and inspect the charge piping/intercooler outlet for coolant residue; scope for white smoke and coolant on the intake side rather than an external leak. Replace the water-to-air intercooler/charge-air cooler unit (genuine OEM core). Because access requires removing intake components in the valley, it is standard practice to also replace the turbo oil strainer, coolant valves, and PCV/oil separator while in there. Refill and bleed the cooling system per procedure. This is a high-difficulty job typically done by a specialist or dealer.

Typical repair cost:$1,500 - $3,500

Research This Issue

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Community Reported
Medium ConfidenceVerifiedReviewed Jun 2026
Community reported
292 owners

On the 2013-2024 Audi S8, the S8 full-size luxury sedan places extreme demands on the air suspension system. All four struts and the compressor commonly need replacement between 60,000-100,000 miles. The heavy curb weight accelerates bladder wear.

Common Symptoms

  • Vehicle sagging after parking
  • Suspension malfunction warning
  • Harsh ride quality
  • Compressor running excessively
  • Uneven ride height
  • Bottoming out over bumps

How to Fix

Replace air struts as they fail. Budget for full system refresh at 80,000 miles. Arnott aftermarket struts offer cost savings.

Typical repair cost:$1,200 - $4,500

Research This Issue

Based on 292 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High Confidence292 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026
Community reported
288 owners

On the 2013-2024 Audi S8, the S8 high-torque application stresses the ZF 8HP torque converter and valve body. Shudder, delayed shifts, and harsh engagement develop as the converter clutch wears and valve body solenoids degrade.

This issue also affects: Audi A4 Avant, Audi A8, Audi S6

Common Symptoms

  • Torque converter shudder
  • Delayed gear engagement
  • Harsh 2-3 shift
  • Transmission fault codes
  • RPM flare on shifts
  • Vibration at highway speed

How to Fix

Replace torque converter and service valve body. Full ZF fluid and filter change every 50,000 miles extends transmission life.

Typical repair cost:$2,500 - $6,000

Research This Issue

Based on 288 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High Confidence288 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026

On the 2013-2018 Audi S8 4.0T TFSI V8, audi TSB 2046724/5 covers sporadic warm-engine no-start or long cranking after the vehicle sits without fully cooling. A rich-mixture DTC may occur, but often there is no DTC. Audi’s procedure distinguishes fuel in the oil from a short-trip profile, ECM software, high-pressure injector leakage and high-pressure fuel-pump leakage rather than assuming one failed component.

Common Symptoms

  • Warm-soak no-start with normal starter operation
  • Long cranking followed by rough running for a few seconds

How to Fix

Have the dealer read DTCs and ODIS fuel-in-oil value, verify ECM software and perform Audi’s high- and low-pressure holding tests. If high-pressure behavior is abnormal, borescope the combustion chamber to identify a leaking injector. If low-side pressure builds correctly but drops more than 1.5 bar in the first 15 minutes, Audi says at least one HPFP may be leaking and directs replacement of both pumps plus an oil change. Select no pump or injector until the test identifies the path.

Owner tips & cautions

  • TipRecord engine temperature and how long the car sat before the hard start; do not approve pumps or injectors without the pressure-hold results.

Research This Issue

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Manually Verified
High ConfidenceVerifiedReviewed Jul 2026

On the 2013-2018 Audi S8 4.0T TFSI V8 (CTFA/CGTA/CWUC), like other VAG direct-injection engines, the 4.0T runs port-bypassing direct injection, so no fuel washes the back of the intake valves. Carbon deposits accumulate on the valves and ports over time, restricting airflow and degrading the seal. Owners report a gradual power loss, rough idle, random (non-cylinder-specific) misfires, and reduced fuel economy, often with no single clear fault code. Buildup is accelerated by short trips, the COD cylinder deactivation, and any oil ingestion from a failing PCV. It is one of the most common drivability complaints on higher-mileage 4.0T cars.

This issue also affects: Audi A4, Audi A1, Audi A5

Common Symptoms

  • Gradual loss of power
  • Rough idle
  • Random misfires not isolated to one cylinder
  • Reduced fuel economy
  • Hesitation under acceleration

How to Fix

Confirm via borescope of the intake valves (and rule out coils/plugs/PCV first). The accepted repair is walnut-shell blasting: remove the intake manifold and media-blast the carbon off the valves and ports with crushed walnut shells, then reinstall with new intake gaskets. Replace spark plugs and inspect coils while the manifold is off. Preventively, keep up with oil changes, fix any PCV/oil-burning source, and consider periodic cleaning every ~40,000-60,000 miles. Catch-can solutions reduce future accumulation.

Typical repair cost:$600 - $1,400

Research This Issue

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Community Reported
Medium ConfidenceVerifiedReviewed Jun 2026

On the 2007-2018 Audi S8, like other large Audi sedans, the S8 relies on sunroof drain channels and cowl/plenum drains to route rainwater away from the cabin and the electronics housed in the plenum area. The plastic drain connectors and channels become brittle and crack, and the plenum drains clog with debris. When they fail, water backs up and finds its way into the cabin through the pollen-filter box or directly onto plenum-mounted control modules, soaking footwells/headliner and potentially short-circuiting sensitive electronics or the brake booster. RepairPal documents rainwater accumulating in the plenum tray due to clogged drains on both the A8 and S8.

This issue also affects: Audi R8

Common Symptoms

  • Wet or damp front footwells after rain
  • Musty smell / damp headliner
  • Water pooling in the plenum/cowl tray
  • Intermittent electrical faults after heavy rain
  • Fogged windows / interior condensation

How to Fix

Clear and flush all sunroof and plenum/cowl drains; replace cracked drain hoses, grommets, or channel connectors. Dry out saturated carpet/insulation and inspect plenum-area modules for corrosion, replacing any water-damaged control units. Preventively clean the drains at least annually and keep the cowl area free of leaves/debris.

Typical repair cost:$200 - $3,500

Research This Issue

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Community Reported
Low ConfidenceVerifiedReviewed Jul 2026
NHTSA Recalls10 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

BACK OVER PREVENTION: SENSING SYSTEM: CAMERA

Volkswagen Group of America, Inc. (Audi) is recalling certain 2021 Audi A8 and S8, 2022 Audi A5 Sportback, A4 Sedan, E-Tron GT, Q3, Q5, RS6 Avant, A3 Sedan, S5 Sportback, Q5 Sportback, Q7, Q8, RSQ8, SQ7, SQ8, and S3 Sedan vehicles. A software error may prevent the rear-view image from initially displaying when the vehicle begins to reverse. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 111, "Rear Visibility."

Campaign #21V82500020/10/2021

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."

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Frequently Asked Questions

What are the most common Audi S8 problems?

According to Au7o's analysis of 823+ owner reports, the 2018 Audi S8 has 7 documented issues. The most frequently reported are: Adaptive Air Suspension Multi-Point Failure, ZF 8-Speed Torque Converter and Valve Body Issues, 4.0T Turbo Coolant System Degradation. Of these, 4 are rated critical and should be addressed promptly.

Is the Audi S8 reliable?

The 2018 Audi S8 has 7 known issues documented across 823+ owner reports. 4 issues are rated critical: Adaptive Air Suspension Multi-Point Failure and ZF 8-Speed Torque Converter and Valve Body Issues and 4.0T Turbo Coolant System Degradation and Water-to-Air Intercooler Internal Coolant Leak (Coolant into Intake). 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 S8 problems?

Repair costs for known Audi S8 issues range from $200 to $6,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Adaptive Air Suspension Multi-Point Failure, typically costs $1,200-$4,500 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2013-2024 Audi S8 Adaptive Air Suspension Multi-Point Failure?

The S8 full-size luxury sedan places extreme demands on the air suspension system. All four struts and the compressor commonly need replacement between 60,000-100,000 miles. The heavy curb weight accelerates bladder wear. Repairs typically run $1,200-$4,500. Severity: high.

What is the 2013-2024 Audi S8 ZF 8-Speed Torque Converter and Valve Body Issues?

The S8 high-torque application stresses the ZF 8HP torque converter and valve body. Shudder, delayed shifts, and harsh engagement develop as the converter clutch wears and valve body solenoids degrade. Repairs typically run $2,500-$6,000. Severity: high.

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 823+ owner reports, NHTSA recalls, TSBs, and automotive forums.

Campaign #21V60600005/08/2021

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.

Campaign #22V03400026/01/2022

ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE (ECU/ECM)

Volkswagen Group of America, Inc. (Audi) is recalling certain 2019-2021 Audi A8 and 2020-2021 Audi S8 vehicles. A missing sealing pin may allow moisture to enter the engine control module connector, possibly causing a control module malfunction.

Campaign #21V11100024/02/2021

+ 5 more recalls. Check all on NHTSA.gov

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

What is the 2013-2024 Audi S8 4.0T Turbo Coolant System Degradation?

The S8 4.0T V8 shares coolant line issues with other 4.0T Audi models but the heavier sedan and higher power tune accelerate wear. Turbo oil and coolant line failures can cause expensive damage if not caught early. Repairs typically run $1,000-$3,500. Severity: high.

What is the 2013-2018 Audi S8 Water-to-Air Intercooler Internal Coolant Leak (Coolant into Intake)?

The 4.0T uses a compact water-to-air charge-air cooler mounted in the hot 'V' between the cylinder banks. The intercooler core can develop an internal leak that allows engine coolant to weep directly into the pressurized intake path. Owners report slow, unexplained coolant loss w… Repairs typically run $1,500-$3,500. Severity: high.

What is the 2013-2018 Audi S8 2013-2018 S8 Warm-Soak Long-Crank or No-Start - Fuel Diagnosis Required?

Audi TSB 2046724/5 covers sporadic warm-engine no-start or long cranking after the vehicle sits without fully cooling. A rich-mixture DTC may occur, but often there is no DTC. Audi’s procedure distinguishes fuel in the oil from a short-trip profile, ECM software, high-pressure in… Severity: medium.

What is the 2013-2018 Audi S8 Direct-Injection Carbon Buildup on Intake Valves (Misfires / Rough Idle)?

Like other VAG direct-injection engines, the 4.0T runs port-bypassing direct injection, so no fuel washes the back of the intake valves. Carbon deposits accumulate on the valves and ports over time, restricting airflow and degrading the seal. Owners report a gradual power loss, r… Repairs typically run $600-$1,400. Severity: medium.

What is the 2007-2018 Audi S8 Clogged Sunroof / Plenum Drains Causing Water Intrusion and Electronics Damage?

Like other large Audi sedans, the S8 relies on sunroof drain channels and cowl/plenum drains to route rainwater away from the cabin and the electronics housed in the plenum area. The plastic drain connectors and channels become brittle and crack, and the plenum drains clog with d… Repairs typically run $200-$3,500. Severity: medium.