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Mercedes-Benz B-Class seat belts and airbags problems

DVSA MOT tests 2022–2025 · 27,268 MOT tests · Updated

At 10 years, 1.8 in 100 MOT tests of the Mercedes-Benz B-Class failed on seat belts and airbags, against 0.7 for all class 4 vehicles the same age (all test years; 27,268 MOT tests) [1].

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  • Against all class 4 vehicles the same age: fails 2.4–2.8× as often as all class 4 vehicles the same age (all test years), 502 MOT tests with a fail
  • By age: seen at 17 ages from 3 to 19 years, 290,232 MOT tests
  • Most common fail: Airbag (SRS) warning light on, 1.5 per 100 MOT tests

Figures are for the model as a whole, not for one car.

What the MOT tests show

What we know

1.8 fails per 100 MOT tests at 10 years, against 0.7 for all class 4 vehicles tested at 10 (all test years). The Mercedes-Benz B-Class fails more often here.

Why it matters

A seat belts and airbags fail stops the car passing until it is fixed; the most common one is rated major by DVSA.

What to check

Pull every seat belt out fully and let it retract, check each buckle latches and releases, and make sure the airbag light goes out after start-up.

Mercedes-Benz B-Class seat belts and airbags fails by age

Mercedes-Benz B-Class seat belts and airbags fails per 100 MOT tests by ageSolid line: the Mercedes-Benz B-Class. Dashed line: all cars the same age. The table below lists every value.01233 years: 0.8 per 100 (all cars 0.3), 10,576 MOT tests34 years: 0.7 per 100 (all cars 0.3), 13,190 MOT tests5 years: 0.6 per 100 (all cars 0.3), 16,988 MOT tests56 years: 0.7 per 100 (all cars 0.4), 19,508 MOT tests7 years: 0.6 per 100 (all cars 0.4), 20,864 MOT tests78 years: 1.0 per 100 (all cars 0.5), 25,189 MOT tests9 years: 1.4 per 100 (all cars 0.6), 26,796 MOT tests910 years: 1.8 per 100 (all cars 0.7), 27,268 MOT tests11 years: 1.8 per 100 (all cars 0.9), 25,350 MOT tests1112 years: 1.7 per 100 (all cars 1.0), 21,871 MOT tests13 years: 1.6 per 100 (all cars 1.2), 19,379 MOT tests1314 years: 1.7 per 100 (all cars 1.5), 17,229 MOT tests15 years: 2.0 per 100 (all cars 1.7), 16,318 MOT tests1516 years: 2.2 per 100 (all cars 2.1), 13,766 MOT tests17 years: 2.6 per 100 (all cars 2.5), 8,986 MOT tests1718 years: 2.2 per 100 (all cars 2.7), 4,909 MOT tests19 years: 2.3 per 100 (all cars 2.9), 2,045 MOT tests19
Fails per 100 MOT tests by age, all first-use years pooled. Mercedes-Benz B-Class All class 4 vehicles the same age Shaded: over 18 years, survivors only.
AgeMOT testsFails per 100All class 4 vehicles the same age
310,5760.80.3
413,1900.70.3
516,9880.60.3
619,5080.70.4
720,8640.60.4
825,1891.00.5
926,7961.40.6
1027,2681.80.7
1125,3501.80.9
1221,8711.71.0
1319,3791.61.2
1417,2291.71.5
1516,3182.01.7
1613,7662.22.1
178,9862.62.5
184,9092.22.7
19*2,0452.32.9

All first-use years of the Mercedes-Benz B-Class pooled at each age, against all class 4 vehicles at that age over all 2022–2025 test years. * Only survivors are still tested at this age.

What fails in the seat belts and airbags at 10 years

Fails

  • Airbag (SRS) warning light on: 1.5 fails per 100 MOT tests, all class 4 vehicles 0.4. Diagnose and fix airbag (SRS) warning: estimated £39–£317 (0.5–1.5 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts £0–£200) Airbag (SRS) warning lamp indicates a fault MOT fail

Diagnose and fix airbag (SRS) warning cost

Repair figures are estimates, not quotes: how we estimate repair costs.

Buying a Mercedes-Benz B-Class? Check that exact car before the viewing.

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  • Model risks for this year and fuel
  • What similar cars did at their next MOT
  • Repairs ahead
  • Viewing checklist

See a sample report

By engine and fuel

  • 1.5 diesel: 2.0 per 100 at 10 years, about average for diesel class 4 vehicles the same age (all test years; 8,654 MOT tests)
  • 2.0 diesel: 1.7 per 100 at 14 years, about average for diesel class 4 vehicles the same age (all test years; 8,429 MOT tests)

How to check on a test drive

Pull every seat belt out fully and let it retract, check each buckle latches and releases, and make sure the airbag light goes out after start-up.

Check one Mercedes-Benz B-Class, not the average

The figures here describe Mercedes-Benz B-Class cars as a group. These free tools answer for one car. Each line says what the tool reads.

Other Mercedes-Benz B-Class problems

Seat belts and airbags on rival models

Questions people ask

Does the Mercedes-Benz B-Class have more seat belts and airbags problems than other cars?

2.4 to 2.8 times the seat belts and airbags fail rate of all class 4 vehicles the same age at 10 years (all test years), from 27,268 MOT tests. The interval is clear of 1.2 in the same direction at 5 of the 17 ages seen (ages up to 18 with at least 100 MOT tests with a fail).

How common are Mercedes-Benz B-Class seat belts and airbags problems?

1.8 in 100 MOT tests at 10 years failed on seat belts and airbags, against 0.7 for all class 4 vehicles the same age (all test years; 27,268 MOT tests).

What is the most common Mercedes-Benz B-Class seat belts and airbags fail?

1.5 in 100 MOT tests at 10 years: Airbag (SRS) warning light on (402 MOT tests with it).

Sources

  1. Driver and Vehicle Standards Agency, Anonymised MOT tests and results, 2022 to 2025. DVSA MOT data, Open Government Licence v3.0, 290,232 MOT tests. Accessed 7 Oct 2026.
  2. Office for National Statistics, Consumer price inflation, local price quotes (car repair items). ONS price quotes, series 610236. Accessed 7 Oct 2026.

Parts: against all class 4 vehicles at the same age, all 2022–2025 test years pooled, not adjusted for mileage. Breakdowns and non-MOT faults are not in this data. How we compare