Does the Mercedes-Benz B-Class fail the MOT on noise, emissions and leaks more than it should?
The Mercedes-Benz B-Class records 2.43 noise, emissions and leaks failure items per 100 initial MOT tests (2019–2024), against 3.23 expected for a car of the same age mix: less than expected for its class and age (−0.80, 95% interval −0.86 to −0.74). It ranks 413 of 678 models on noise, emissions and leaks (1 = most failures above expected).
Data release dvsa-2024-v2 (24 Sep 2026) · page updated 30 Sep 2026 · all models on noise, emissions and leaks · check a Mercedes-Benz B-Class by registration
What exactly fails on noise, emissions and leaks?
The most frequent DVSA defect wording in this group on the Mercedes-Benz B-Class is “Engine MIL illuminated indicating a malfunction”, recorded 6,167 times in 2019–2024.
| DVSA defect wording | Items | Per 100 tests |
|---|---|---|
| Engine MIL illuminated indicating a malfunction | 6,167 | 1.58 |
| Smoke opacity levels exceed the manufacturer's specified limit | 1,371 | 0.35 |
| Emissions test unable to be completed | 428 | 0.11 |
| Lambda coefficient outside the default limits or the range specified by the manufacturer | 359 | 0.09 |
| Smoke opacity levels exceed default limit | 306 | 0.08 |
Source: DVSA MOT bulk data (OGL v3.0) · Window: 2019–2024 · n = 391,293 (initial tests) · Method: failure items (major and minor) grouped by DVSA's defect tree; wordings with 30+ items · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV
If a Mercedes-Benz B-Class gets a noise, emissions and leaks advisory, how often does it fail next time?
5.6% of Mercedes-Benz B-Class MOTs with a noise, emissions and leaks advisory were followed by a fail in the same group at the next MOT, typically 12.1 months and 5,205 miles later (2,985 advisories followed).
Source: DVSA MOT bulk data (OGL v3.0) · Window: 2019–2024 · n = 2,985 (advisories followed) · Method: the same vehicles followed to their next ordinary MOT · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV
Other pages for this model
Mercedes-Benz B-Class 2005 · Mercedes-Benz B-Class 2006 · Mercedes-Benz B-Class 2007 · Mercedes-Benz B-Class 2008 · Mercedes-Benz B-Class 2009 · Mercedes-Benz B-Class 2010 · Mercedes-Benz B-Class 2011 · Mercedes-Benz B-Class 2012 · Mercedes-Benz B-Class 2013 · Mercedes-Benz B-Class 2014 · Mercedes-Benz B-Class 2015 · Mercedes-Benz B-Class 2016 · Mercedes-Benz B-Class 2017 · Mercedes-Benz B-Class 2018 · Mercedes-Benz B-Class 2019 · Mercedes-Benz B-Class 2020 · Mercedes-Benz B-Class in Norway · Mercedes-Benz B-Class in Finland · Mercedes-Benz B-Class in the Netherlands · Mercedes-Benz B-Class by postcode area · Mercedes-Benz B-Class body, chassis and structure failures · Mercedes-Benz B-Class brakes failures · Mercedes-Benz B-Class vehicle identification failures · Mercedes-Benz B-Class lamps, reflectors and electrics failures · Mercedes-Benz B-Class road wheels failures · Mercedes-Benz B-Class seat belts and airbags failures · Mercedes-Benz B-Class steering failures · Mercedes-Benz B-Class suspension failures · Mercedes-Benz B-Class tyres failures · Mercedes-Benz B-Class visibility failures