MOT failure data · 2025

Mercedes-Benz B-Class MOT problems

Across every Mercedes-Benz B-Class that failed its 2025 MOT, the defect testers recorded most often was coil spring fractured or broken, on 7.84% of failure items. The broadest problem area was suspension at 25.46%. These are recorded defects across the model, not a diagnosis of any one car.

Most common Mercedes-Benz B-Class MOT failures

#	Recorded defect	Area	Share
1	Coil spring fractured or broken	Suspension	7.84%
2	Linkage ball joint dust cover ball joint dust cover no longer prevents the ingress of dirt	Suspension	6.53%
3	Joints constant velocity boot split or insecure, no longer prevents the ingress of dirt	Body, chassis, structure	4.72%
4	Ball joint ball joint excessively worn	Suspension	4.19%
5	Registration plate lamp(s) inoperative in the case of a single lamp or all lamps	Lamps, reflectors and electrical equipment	3.75%
6	Malfunction indicator lamp inoperative or indicates a malfunction	Noise, emissions and leaks	3.64%
7	Condition has a cut in excess of the requirements deep enough to reach the ply or cords	Tyres	3.28%
8	Tread depth tread depth below requirements of 1.6mm	Tyres	3.22%
9	Brake pads less than 1.5 mm thick	Brakes	3.2%
10	Condition has ply or cords exposed	Tyres	3.18%

Shares are of all recorded failure items for this model, so they sum to less than 100% — a single failed test often records several defects, and the long tail below the top 10 is not shown.

What this means if you are buying one

Use it as a viewing checklist. If you are looking at a Mercedes-Benz B-Class, these are the areas worth inspecting and worth asking about — and worth reading the car's own MOT history for, since a defect that keeps reappearing as an advisory is a better signal than any model-wide average.

The MOT record also has hard limits: it does not check the engine, clutch or gearbox, and it says nothing about outstanding finance, insurance write-off history, stolen markers or whether the mileage is genuine. Our used Mercedes-Benz B-Class buying guide covers what to check beyond the MOT.

Checking a specific Mercedes-Benz B-Class?

Enter its registration for finance, write-off, stolen, mileage and keeper history.

Other Mercedes-Benz models

Mercedes-Benz B-Class MOT FAQs

What does a Mercedes-Benz B-Class most commonly fail its MOT on?

The single most recorded defect on Mercedes-Benz B-Class cars failing their 2025 MOT was "coil spring fractured or broken", appearing on 7.84% of failure items.

Does this mean my Mercedes-Benz B-Class will fail?

No. This is what testers recorded across every Mercedes-Benz B-Class that failed in 2025. It shows where this model tends to need attention, not the condition of any individual car. The Mercedes-Benz B-Class passed 74.91% of its initial tests.

How do I see a specific Mercedes-Benz B-Class's MOT history?

Enter its registration on our free MOT history check to see that car's own test results, advisories and recorded mileages.

Defect counts from the DVSA MOT Anonymised test-item data for 2025 (class 4 initial tests, failure items only — advisories and minor defects excluded), licensed under the Open Government Licence v3.0.