2019 Mercedes-Benz B-Class — MOT failures & pass rate
Across 18,488 MOT tests, the 2019 Mercedes-Benz B-Class recorded a 92.7% pass rate. That is 4.2 percentage points better than MPVs of a similar age, which fail at 11.5%. Failures cluster in tyres, lighting & signalling and seat belts & restraints.
What the MOT record shows
No single area dominates — tyres (4.2%) and lighting & signalling (1.7%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, tread depth and srs malfunction indicator lamp — headlamp aim alone was recorded 286 times.
Mileage is the strongest signal on the record: 5.9% of 0-30k cars fail, rising to 18.3% once past 90-120k — 3.1× the risk.
Fuel type barely separates them — petrol fails 6.8% of the time against 8.1% for diesel.
Advisories point at the next bill rather than this one: tyres was flagged on 20.3% of tests without failing them.
The trend is worsening — 6.1% of tests failed in 2021 against 8.3% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.2% | 782 |
| 2 | Lighting & signalling | 1.7% | 319 |
| 3 | Seat belts & restraints | 1.4% | 253 |
| 4 | Visibility | 1.2% | 219 |
| 5 | Brakes | 0.9% | 166 |
| 6 | Suspension | 0.5% | 85 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Headlamp aim | 286 |
| 2 | Tread depth | 219 |
| 3 | SRS malfunction indicator lamp | 191 |
| 4 | Wipers | 173 |
| 5 | Brake pads | 144 |
| 6 | Washers | 57 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Tyres | 20.3% | 3,758 |
| 2 | Brakes | 7.0% | 1,292 |
| 3 | Other defects | 4.7% | 867 |
| 4 | Visibility | 2.8% | 511 |
| 5 | Suspension | 2.3% | 429 |
| 6 | Lighting & signalling | 0.5% | 98 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 0-30k | 12,267 | 5.9% |
| 30-60k | 5,473 | 9.6% |
| 60-90k | 631 | 12.0% |
| 90-120k | 82 | 18.3% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 11,657 | 6.8% |
| Diesel | 6,831 | 8.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 131 | 6.1% |
| 2022 | 4,572 | 5.9% |
| 2023 | 4,621 | 7.0% |
| 2024 | 4,531 | 7.9% |
| 2025 | 4,633 | 8.3% |
What to check before buying a 2019 B-Class
On a 2019 B-Class, tyres is what the MOT record says goes wrong most — it appeared in 4.2% of tests. Check these areas before you commit.
- Tyres (4.2% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Lighting & signalling (1.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Seat belts & restraints (1.4% of tests): Belt damage or faulty pretensioners — usually straightforward but safety-critical. Typical repair: £50–£300.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 2019 Mercedes-Benz B-Classs pass their MOT?
92.7% of the 18,488 2019 Mercedes-Benz B-Class MOT tests in this dataset passed — a 7.3% fail rate.
What is the most common MOT failure on a 2019 Mercedes-Benz B-Class?
Tyres, recorded in 4.2% of tests, followed by lighting & signalling (1.7%).
Does the 2019 B-Class get worse with mileage?
Its MOT fail rate rises from 5.9% in the 0-30k band to 18.3% in the 90-120k band.
Methodology & source. Based on 18,488 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.