2021 · 3 years old at test · Petrol mostly

2021 Mercedes-Benz B-Class MOT pass rate and common faults

1,882 MOT tests in 2024. 90.9% passed first time, compared with 87.6% for all cars the same age.

104Above average
Passed first time90.9%
Failed or needed repairs9.1%
Typical mileage at test19,000

Most common reasons for failing

Share of all 1,882 tests where this item caused a failure.

  1. Tyres - condition: has a cut in excess of the requirements deep enough to reach the ply or cords2.9%
  2. Wipers: does not clear the windscreen effectively1.3%
  3. Tyres - condition: has ply or cords exposed1.0%
    25 marked dangerous
  4. Headlamp aim: too low0.6%
  5. Headlamp aim: too high0.4%
  6. Tyres - condition: has a bulge, caused by separation or partial failure of its structure0.4%
    8 marked dangerous
  7. Brake pads: less than 1.5 mm thick0.3%
    6 marked dangerous
  8. Tread depth below requirements of 1.6mm0.2%
    6 marked dangerous
  9. Tyres - condition: has a lump, caused by separation or partial failure of its structure0.2%
    4 marked dangerous

Problem areas

Failure items found per 100 tests, by part of the car.

  1. Tyres5.6%
  2. Visibility (wipers, screen, mirrors)1.6%
  3. Lights & electrics1.6%
  4. Brakes0.6%
  5. Seat belts & airbags0.4%
  6. Emissions & leaks0.3%
  7. Body & chassis0.2%
  8. Number plates & VIN0.2%

Most common advisories

Not failures yet, but things the tester warned about.

  1. Tread depth below requirements of 1.6mm7.3%
  2. Tyres - condition: has a tear, caused by separation or partial failure of its structure5.1%
  3. Tyres - condition: has a cut in excess of the requirements deep enough to reach the ply or cords2.1%
  4. Brake pads: less than 1.5 mm thick1.9%
  5. Non-component advisories: Nail in tyre1.8%

What this means if you are buying one

This model year does better than most cars its age, so it is a reasonable used buy on MOT record alone. Before buying, check the area that fails most: tyres - condition: has a cut in excess of the requirements deep enough to reach the ply or cords. Then look up the car's own MOT history on GOV.UK with its number plate, and look for repeat advisories.

← 2020 B-ClassAll B-Class years

Questions

What is the MOT pass rate for a 2021 Mercedes-Benz B-Class?

In 2024, 90.9% of 2021 Mercedes-Benz B-Class cars passed their MOT first time, across 1,882 tests. The average for all 3-year-old cars was 87.6%.

What are the most common MOT failures on a 2021 Mercedes-Benz B-Class?

The most common failure reasons were tyres - condition: has a cut in excess of the requirements deep enough to reach the ply or cords; wipers: does not clear the windscreen effectively; tyres - condition: has ply or cords exposed. The biggest problem area was tyres.

Is the 2021 Mercedes-Benz B-Class reliable at MOT time?

Its MOT Rank score is 104, which is above average for a car of its age (100 means exactly average).