The Engine Control Module (ECM) can suffer from moisture ingress due to a missing sealing pin, leading to module malfunction and potential engine issues. This is a critical failure mode. Estimated repair cost: $1,500 - $3,000+.

Rear Seat Belt Retractor Malfunction

Rear seat belt locking retractors may deactivate early, compromising the security of child restraint systems. This is a significant safety concern. Estimated repair cost: $300 - $800.

Instrument Panel Display Failure

Software vulnerabilities can lead to failures in the instrument panel display, affecting the driver's access to critical vehicle information. Estimated repair cost: $800 - $1,500.

Rear Axle Alignment Issues

Recurring issues with rear axle alignment can lead to uneven tire wear and compromised handling. This has been subject to multiple recalls. Estimated repair cost: $400 - $900.

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2021 Audi S8 Maintenance guide

Name: Maintenance dataset for 2021 Audi S8
Creator: Carfocal

v1.0Updated Jun 2, 2026Daniel Wilson4 Sources Analyzed2 Critical Recalls

MAINTENANCE SUMMARY

The 2021 Audi S8 demands diligent maintenance, with a focus on addressing potential ECM moisture ingress and rear seat belt retractor issues. Its 'Below Average' reliability verdict, underscored by 54 recalls and 254 TSBs, necessitates proactive inspections and adherence to service schedules.

View Critical Issue: ECM Moisture Ingress

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Reliability Score

Est. Annual Maintenance Cost

$600 - $1,000

TSBs & Recalls

254 TSBs | 54 Recalls

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Key Takeaways

Proactive maintenance is essential due to the 'Below Average' reliability verdict.
Prioritize inspections and repairs related to ECM moisture ingress and rear seat belt function.

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Critical service intervals

Common failure analysis

Symptoms and prevention guidance