Seat Belt Retractor Malfunction

Potential deactivation of the Automatic Locking Retractor (ALR) in the seat belts can compromise occupant crash protection. This affects the seat belt's ability to secure occupants during sudden stops or collisions. Estimated repair cost: $300 - $700.

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2021 BMW M4 Maintenance guide

Name: Maintenance dataset for 2021 BMW M4
Creator: Carfocal

v1.0Updated Jun 4, 2026Ryan Davis4 Sources Analyzed2 Critical Recalls

MAINTENANCE SUMMARY

The 2021 BMW M4 demands diligent maintenance, with a critical focus on ensuring all safety recalls, particularly those concerning the braking system and seat belts, are fully addressed. Regular fluid changes and inspections are key to preventing potential issues, though no specific widespread mechanical failures are heavily documented beyond recall items.

View Critical Issue: Integrated Brake System Failure

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Reliability Score

Est. Annual Maintenance Cost

$800 - $1,500

TSBs & Recalls

1 TSBs | 5 Recalls

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Key Takeaways

Prioritize completion of all safety recalls, especially for the braking system and seat belts.
Adhere to a strict 10,000-mile oil change interval using 5W-30 synthetic oil.

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Critical service intervals

Common failure analysis

Symptoms and prevention guidance