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Audi · Known Issues

2018 Audi A5 Problems: 2 Known Issues

2018 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated September 2026

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Issue summary

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2018 Audi A5 has 2 documented known issues, with 1 rated critical. The most serious is 2018-2020 Audi A5 Passenger-Airbag Recall 74E3 / NHTSA 21V874. Across all issues with published estimates, repair costs range from $700 to $1,800. DIY maintenance guides at au7o.io.

In This Article

  • A5 Safety/Recalls1
  • A5 Engine1
  • Recalls8
  • FAQ
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In This Article

  • Safety/Recalls1
  • Engine1
  • Recalls8
  • FAQ

All 2 Known Issues

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ALL YEARS20242023202220212020201920182017201620152014201320122011201020092008

On the 2018-2020 Audi A5, nHTSA campaign 21V874 / Audi 74E3 covers certain 2018-2020 A5 Coupe, Sportback and Cabriolet vehicles. A contact fault in the cable between the passenger-seat heater and Passenger Occupant Detection System can be misdiagnosed by the software and disable the passenger airbag, increasing injury risk in a crash. The campaign expands recall 19V547 / 74D9, and previously repaired vehicles must return for the new remedy. Eligibility is VIN-specific.

Common Symptoms

  • Passenger-airbag warning indicator illuminated
  • Passenger airbag shown as disabled with an occupant present

How to Fix

Check the VIN and campaign-completion history with Audi or NHTSA. The free remedy replaces the connecting cable and either the heating mat or the entire seat cover. If the passenger-airbag warning or AIRBAG OFF indicator behaves unexpectedly, avoid using that seating position until Audi inspects it. Do not buy a clock spring for this campaign.

Research This Issue

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NHTSA Verified
High ConfidenceVerifiedReviewed Jul 2026

On the 2008-2023 Audi A5, all direct-injection engines in the A5 and S5 (2.0 TFSI, 3.0T, and 3.2L V6) suffer from severe carbon buildup on intake valves. In direct-injection engines, fuel sprays directly into the cylinder, bypassing the intake valves. This means intake valves are only exposed to oil vapors from the PCV system, which bake onto the valve backs as hard carbon deposits. Over 60,000-100,000 miles, carbon restricts airflow, causing rough idle, misfires, hesitation, and power loss. The 3.0T supercharged S5 is particularly susceptible due to higher oil vapor pressure. In severe cases, carbon deposits prevent valves from seating properly, causing compression loss and valve damage. The ONLY effective fix is walnut blasting—blasting crushed walnut shells through the intake to remove carbon. A5OC forums recommend this as preventive maintenance every 60,000 miles.

This issue also affects: Audi S8, Audi A4, Audi A1

Common Symptoms

  • Rough or unstable idle (engine shakes at stoplights)
  • Hesitation or stumbling on acceleration
  • Reduced power and sluggish throttle response
  • Poor fuel economy (2-4 MPG drop)
  • Check engine light with misfire codes (P0300-P0306)
  • Engine runs rough when cold, smooths out when warm
  • Hard starting or extended cranking

How to Fix

WALNUT BLASTING: Remove intake manifold and blast crushed walnut shells through intake ports to remove carbon ($700-$1,200). Requires specialized equipment—DIY not recommended unless experienced. Dealers charge $1,200-$1,800; independent Audi shops charge less. Repeat every 60,000-80,000 miles as preventive maintenance. PREVENTION: Install catch can ($300-$500) to filter PCV oil vapors before they reach intake valves—extends cleaning interval to 100k+ miles. Add Liqui Moly Intake Valve Cleaner to every oil change ($15). Perform "Italian tune-up" monthly (spirited highway driving to high RPM).

Typical repair cost:$700 - $1,800

Research This Issue

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Community Reported
Medium Confidence
NHTSA Recalls8 recalls

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

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."

Campaign #22V80600026/10/2022
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Other Audi Models

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Frequently Asked Questions

What are the most common Audi A5 problems?

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2018 Audi A5 has 2 documented issues. The most frequently reported are: 2018-2020 Audi A5 Passenger-Airbag Recall 74E3 / NHTSA 21V874, Severe Carbon Buildup on Intake Valves (Direct Injection). Of these, 1 is rated critical and should be addressed promptly.

Is the Audi A5 reliable?

The 2018 Audi A5 has 2 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 1 issue is rated critical: 2018-2020 Audi A5 Passenger-Airbag Recall 74E3 / NHTSA 21V874. 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 A5 problems?

Repair costs for known Audi A5 issues range from $700 to $1,800, 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 2018-2020 Audi A5 2018-2020 Audi A5 Passenger-Airbag Recall 74E3 / NHTSA 21V874?

NHTSA campaign 21V874 / Audi 74E3 covers certain 2018-2020 A5 Coupe, Sportback and Cabriolet vehicles. A contact fault in the cable between the passenger-seat heater and Passenger Occupant Detection System can be misdiagnosed by the software and disable the passenger airbag, incr… Severity: high.

What is the 2008-2023 Audi A5 Severe Carbon Buildup on Intake Valves (Direct Injection)?

All direct-injection engines in the A5 and S5 (2.0 TFSI, 3.0T, and 3.2L V6) suffer from severe carbon buildup on intake valves. In direct-injection engines, fuel sprays directly into the cylinder, bypassing the intake valves. This means intake valves are only exposed to oil vapor… Repairs typically run $700-$1,800. 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 compiled from NHTSA recalls, manufacturer TSBs, automotive forums, and AI-assisted research. No aggregated owner-report counts available for this vehicle yet.

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

EXTERIOR LIGHTING:TAIL LIGHTS

Volkswagen Group of America, Inc. (Audi) is recalling certain 2021 Audi RS5 Sportback, 2020-2021 Audi A5 Sportback, and S5 Sportback vehicles. The wiring harness for the rear lights could be missing the anti-abrasion protection in the area of the spare wheel well.

Campaign #20V73700025/11/2020

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

+ 3 more recalls. Check all on NHTSA.gov

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