Used buying checklist
Mercedes-Benz B Class reliability, common problems and used buying checks
A used Mercedes-Benz B Class looks about average for reliability in UK MOT data: 19.3% of 80,952 tests failed, compared with 18.7% across all indexed models. A good example should have a clean MOT history for corrosion and structure, suspension and steering, and lights and electrical.
It can be, if the exact car has a clean history for corrosion and structure, suspension and steering, and lights and electrical.
Start with corrosion and structure, suspension and steering, and lights and electrical, then compare the car's mileage and recall record below.
Sources used: DVSA MOT tests (Apr 2026); vehicle recalls (Apr 2026); MOT fault wording (May 2025). MOT data does not capture every reliability issue, especially intermittent engine, gearbox or infotainment faults that do not appear during the test.
- 19.3% MOT failure rate
- Median tested mileage 68,352 miles
- 15,614 failed MOT tests analysed
Corrosion and structure is the clearest area to check
Corrosion and structure is the clearest named problem area in this model's MOT history (20.8 MOT notes per 100 tests). Example MOT phrases from this area include corroded and seriously weakened, corroded so that its cross sectional area is reduced and seriously weakened, and excessively corroded.
Example MOT phrases to search in the car's history:
- corroded and seriously weakened
- corroded so that its cross sectional area is reduced and seriously weakened
- excessively corroded
- ferrule excessively corroded
- Play in steering rack inner joint(s)
- ball joint excessively worn
- ball joint dust cover no longer prevents the ingress of dirt
- ball joint dust cover severely deteriorated
- warning lamp indicates a fault
- warning lamp indicates an ABS fault
Focus on corrosion and structure, suspension and steering, and lights and electrical
The model's recorded failure rate is 19.3%, +0.6 percentage points compared with the average across all models. Use the seller questions below to check whether repeat MOT notes have actually been repaired.
- MOT tests analysed80,952 tests
- Median tested mileage68,352 miles
- Failed MOT tests15,614
Should you buy a used Mercedes-Benz B Class?
80.7% of the MOT tests we analysed for this model passed. The model's recorded failure rate is 19.3%, +0.6 percentage points compared with the average across all models. This is a buying brief for the exact car in front of you: clean repeat history matters more than badge reputation.
- Repeat unresolved MOT notes for corrosion and structure, suspension and steering, and lights and electrical
- corrosion and structure appearing across more than one MOT
- Any dangerous MOT failure on the exact car, especially if the same area appears again later
- A seller who cannot explain MOT wording such as "corroded and seriously weakened"
It can be, if the exact car has a clean history for corrosion and structure, suspension and steering, and lights and electrical.
Start with corrosion and structure, suspension and steering, and lights and electrical, then compare the car's mileage and recall record below.
Corrosion and structure is the clearest named problem area in the MOT history (20.8 MOT notes per 100 tests). These counts are issue notes, not failure rates, because a single MOT can list several faults.
Past 100k miles on the Mercedes-Benz B Class, MOT records most often point to corrosion and structure, suspension and steering, and lights and electrical.
The MOT failure rate rises from 0.0% at 0-3 years to 27.7% at 15+ years. Compare the car with the nearest age range before treating a fault as normal wear or a warning sign. The average MOT failure rate across all models in the same dataset is 18.7%.
Start with corrosion and structure, suspension and steering, lights and electrical, and windscreen, wipers, and mirrors. The checklist on this page explains why each area is being recommended, what to inspect, and what to ask the seller.
No relevant recall notices are listed in this report, but recall completion is tied to the exact vehicle, so the seller should still be able to prove recall status.
What should I check first?
Start with corrosion and structure, suspension and steering, lights and electrical, and windscreen, wipers, and mirrors. The checklist on this page explains why each area is being recommended, what to inspect, and what to ask the seller. Each item shows whether it comes from MOT results, recall notices, or a standard used-car check.
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Corrosion and structure Seen in MOT results
Corrosion and structure is one of the most common MOT problem areas for this model (20.8 MOT notes per 100 tests).
What to check: Inspect sills, subframes, mounting points, arches, and underside corrosion advisories.
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Suspension and steering Seen in MOT results
Suspension and steering is one of the most common MOT problem areas for this model (16.8 MOT notes per 100 tests).
What to check: Listen for knocks, check uneven tyre wear, and inspect steering play.
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Lights and electrical Seen in MOT results
Lights and electrical is one of the most common MOT problem areas for this model (8.9 MOT notes per 100 tests).
What to check: Check every lamp, warning light, horn, battery condition, and dashboard messages.
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Windscreen, wipers, and mirrors Seen in MOT results
Windscreen, wipers, and mirrors is one of the most common MOT problem areas for this model (6.1 MOT notes per 100 tests).
What to check: Check windscreen damage, wiper operation, washers, mirrors, and demisting.
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Emissions, engine, and exhaust Seen in MOT results
Emissions, engine, and exhaust is one of the most common MOT problem areas for this model (4.5 MOT notes per 100 tests).
What to check: Check warning lights, smoke, exhaust leaks, recent emissions failures, and service history.
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Tyres and wheels Seen in MOT results
Tyres and wheels is one of the most common MOT problem areas for this model (1.9 MOT notes per 100 tests).
What to check: Check tyre age, tread depth, sidewall damage, wheel condition, and alignment wear.
What changes with mileage?
Past 100k miles on the Mercedes-Benz B Class, MOT records most often point to corrosion and structure, suspension and steering, and lights and electrical.
Common MOT problem areas
Common faults: what usually fails on this model?
Corrosion and structure is the clearest named problem area in the MOT history (20.8 MOT notes per 100 tests). These counts are issue notes, not failure rates, because a single MOT can list several faults.
Mileage and age checks
Mileage changes: what starts showing up after high mileage?
Past 100k miles on the Mercedes-Benz B Class, MOT records most often point to corrosion and structure, suspension and steering, and lights and electrical. On lower-mileage cars, the most common named areas are corrosion and structure, lights and electrical, and suspension and steering.
| Mileage range | Tests | Vehicles | Failure rate (vs all models) | Median mileage |
|---|---|---|---|---|
| 0-50k | 23,905 | 20,862 | 11.0%+0.2 percentage points vs all models | 35,084 miles |
| 50-100k | 40,182 | 31,252 | 20.9%+0.2 percentage points vs all models | 72,560 miles |
| 100-150k | 14,391 | 10,354 | 27.7%+1.5 percentage points vs all models | 115,607 miles |
| 150-200k | 1,855 | 1,339 | 29.3%+2.0 percentage points vs all models | 162,862 miles |
| 200k+ | 155 | 114 | 29.0%+2.5 percentage points vs all models | 213,721 miles |
Problem areas by mileage
Past 100k miles on the Mercedes-Benz B Class, MOT records most often point to corrosion and structure, suspension and steering, and lights and electrical.
| Mileage range | Car areas most often recorded | Specific MOT defect examples |
|---|---|---|
| 0-50k |
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| 50-100k |
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| 100-150k |
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| 150-200k |
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| 200k+ |
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Fair comparisons: is this problem normal for its age?
The MOT failure rate rises from 0.0% at 0-3 years to 27.7% at 15+ years. Compare the car with the nearest age range before treating a fault as normal wear or a warning sign. The average MOT failure rate across all models in the same dataset is 18.7%. The highest failure rate by age is 27.7% for 15+ years cars, based on 10,564 tests.
| Age range | Tests | Vehicles | Failure rate (vs all models) | Median age |
|---|---|---|---|---|
| 0-3 years 2023–2026 reg. |
5 | 5 | 0.0%-8.4 percentage points vs all models | 2.8 years |
| 3-6 years 2020–2023 reg. |
8,630 | 7,623 | 9.9%-0.7 percentage points vs all models | 5.1 years |
| 6-10 years 2016–2020 reg. |
30,411 | 25,198 | 14.9%-1.7 percentage points vs all models | 8.5 years |
| 10-15 years 2011–2016 reg. |
31,342 | 23,571 | 23.2%-0.3 percentage points vs all models | 12.5 years |
| 15+ years pre-2011 reg. |
10,564 | 7,615 | 27.7%+1.8 percentage points vs all models | 16.2 years |
Recall records and data freshness
Recall context: are there safety notices to know about?
No relevant recall notices are listed in this report, but recall completion is tied to the exact vehicle, so the seller should still be able to prove recall status.
| No relevant recall notices are listed here. Recall completion is still vehicle-specific, so check the exact car with the manufacturer or DVSA. |
Related searches
Common ways people look up the Mercedes-Benz B Class. Each link runs the search and lands on the relevant section of this report.
Related reliability guides
See where this model sits against other Mercedes-Benz reports by MOT failure rate and common problem area.
Compare high-confidence model reports across all makes.
Use the fleet mileage baseline before checking this model's own mileage table.
Compare this model's age pattern with the wider MOT baseline.
Sources used: DVSA MOT tests (Apr 2026); vehicle recalls (Apr 2026); MOT fault wording (May 2025). These are patterns from many MOT tests and recall notices. They help you decide what to inspect and what to ask; they do not certify the condition of one specific car.