UK Reliability Directory

Mercedes-Benz S-Class (W221)

Production Years: 2005 - 20133 Documented Faults

The Mercedes-Benz S-Class (W221) is a refined, imposing, and significantly better-built luxury flagship that remains relatively affordable to buy used. Positioned to reclaim the brand's reputation for quality after the rusty W220, it offers an exceptionally quiet ride, supreme motorway comfort, and vast interior space. In the UK, the S320 and S350 diesels dominate the used market, offering reasonable fuel economy but carrying hefty repair risks for complex systems. The main ownership risks are Airmatic and ABC suspension failures, COMMAND unit glitches, and the high cost of parts, making it best suited for luxury bargain hunters with a solid maintenance fund.

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Common Faults & Reliability

These are the most common documented problems for the Mercedes-Benz S-Class (W221), sorted by their typical impact and frequency.

Airmatic / ABC suspension failure

high severity

Air springs leak and compressors wear out. ABC (Active Body Control) hydraulic systems on sport models are even more expensive to repair. Cars sag on one corner and throw suspension warnings.

Est. repair cost:£800–£3,000

M273 V8 balance shaft sprocket wear

high severity

The V6 and V8 M273 engines can suffer from balance shaft sprocket wear, which alters engine timing and can lead to catastrophic failure if not caught early.

Est. repair cost:£2,000–£4,000

COMAND infotainment glitches

low severity

The COMAND system can develop disc read errors, screen freezing and audio dropouts. Replacement units are very expensive.

Est. repair cost:£200–£800

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