MOT failure data · 2025
Mercedes-Benz 300 MOT problems
Across every Mercedes-Benz 300 that failed its 2025 MOT, the defect testers recorded most often was ball joint dust cover ball joint dust cover no longer prevents the ingress of dirt, on 4.05% of failure items. The broadest problem area was lamps, reflectors and electrical equipment at 25.49%. These are recorded defects across the model, not a diagnosis of any one car.
Most common Mercedes-Benz 300 MOT failures
| # | Recorded defect | Area | Share |
|---|---|---|---|
| 1 | Ball joint dust cover ball joint dust cover no longer prevents the ingress of dirt | Suspension | 4.05% |
| 2 | Component mounting prescribed areas prescribed area excessively corroded significantly reducing structural strength | Suspension | 3.92% |
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 2 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 300, 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 300 buying guide covers what to check beyond the MOT.
Checking a specific Mercedes-Benz 300?
Enter its registration for finance, write-off, stolen, mileage and keeper history.
Other Mercedes-Benz models
- Mercedes-Benz A-Class MOT problems
- Mercedes-Benz GLA MOT problems
- Mercedes-Benz Vito MOT problems
- Mercedes-Benz GLC MOT problems
- Mercedes-Benz CLA MOT problems
- Mercedes-Benz B-Class MOT problems
Mercedes-Benz 300 MOT FAQs
What does a Mercedes-Benz 300 most commonly fail its MOT on?
The single most recorded defect on Mercedes-Benz 300 cars failing their 2025 MOT was "ball joint dust cover ball joint dust cover no longer prevents the ingress of dirt", appearing on 4.05% of failure items.
Does this mean my Mercedes-Benz 300 will fail?
No. This is what testers recorded across every Mercedes-Benz 300 that failed in 2025. It shows where this model tends to need attention, not the condition of any individual car. The Mercedes-Benz 300 passed 81.76% of its initial tests.
How do I see a specific Mercedes-Benz 300's MOT history?
Enter its registration on our free MOT history check to see that car's own test results, advisories and recorded mileages.
See also: Mercedes-Benz 300 MOT pass rate · used Mercedes-Benz 300 buying guide · free MOT history check
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.