Mercedes Benz B MOT Failures
An analysis of 16,127 real DVSA MOT tests on the Mercedes Benz B — what fails, how often, and how that compares to every other car on UK roads.
Where the Mercedes Benz B fails its MOT
The single biggest MOT failure point on the Mercedes Benz B is emissions failure — this model is 11 times more likely to fail on this item than the average car on UK roads. That makes it worth watching for anyone buying or owning this model. Across 16,127 MOT tests, 1.92% of all Mercedes Benz B tests recorded this as a failure.
Exhaust and emissions failures often point to catalytic converter degradation, lambda sensor faults, or — in diesel models — DPF problems. These can be expensive to fix and will cause an immediate MOT failure.
Other notable weak points include light unit fault (7.5x the fleet average) and brake fluid significantly below minimum mark (6.4x the fleet average). These ratios compare the Mercedes Benz B's failure rate on each item against the national average for all cars tested — a ratio of 10x means this model fails ten times more often than a typical car.
The failures span 3 categories: Exhaust & Emissions, Seatbelts & Airbags, Brakes. If you're inspecting a Mercedes Benz B before purchase, these are the areas to focus on — and if any have been flagged as advisories on a previous MOT, they're likely to become failures in the near future.
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What to check before buying a Mercedes Benz B
Based on the MOT failure data and known issues above, here's what to prioritise when inspecting a Mercedes Benz B:
Exhaust & Emissions — check for emissions failure. Seatbelts & Airbags — check for light unit fault. Brakes — check for brake fluid significantly below minimum mark.
Always check the car's full MOT history for patterns — recurring advisories often become failures within 12 months. Enter any reg into our free car check to see the complete picture.
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Mercedes Benz B MOT FAQs
What are the most common MOT failures on a Mercedes Benz B?
Based on 16,127 DVSA MOT tests, the most common failure is emissions failure — at 11x the national fleet average. Other frequent failures include light unit fault and brake fluid significantly below minimum mark.
Is the Mercedes Benz B reliable based on MOT data?
The Mercedes Benz B has 3 categories where it fails more often than average. The main concern is emissions failure. Always check a specific car's full history before buying.
What MOT failures should I expect at high mileage?
The most common high-mileage failures include emissions failure, light unit fault, brake fluid significantly below minimum mark.
How do I check a Mercedes Benz B's MOT history?
Enter the registration number into our free car check above. You'll see every MOT test result, advisories and failures, mileage readings, write-off status, and finance checks.
MOT failure data sourced from DVSA bulk test records via data.gov.uk. Ratios compare this model's failure rate against the national fleet average. Known issues sourced from manufacturer bulletins, specialist workshops, and verified owner reports.