2009 Mercedes-Benz B-Class — MOT failures & pass rate
Across 30,409 MOT tests analysed for the 2009 Mercedes-Benz B-Class, the most common recorded failure areas were lighting & signalling, suspension and brakes. Its pass rate of 74.3% was above the average for MPVs of a similar age (72.8%). Higher-mileage examples failed more often — 29.5% in the 150k+ group versus 13.4% in the 0-30k group.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 12.9% | 3,915 |
| 2 | Suspension | 11.7% | 3,569 |
| 3 | Brakes | 10.0% | 3,039 |
| 4 | Body, structure & corrosion | 5.7% | 1,746 |
| 5 | Tyres | 5.1% | 1,552 |
| 6 | Visibility | 4.9% | 1,486 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Coil spring | 1,735 |
| 2 | Rigid brake pipes | 1,526 |
| 3 | Joints | 1,515 |
| 4 | Headlamp aim | 1,416 |
| 5 | Ball joint | 1,303 |
| 6 | Washers | 1,041 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 39.7% | 12,080 |
| 2 | Tyres | 27.2% | 8,255 |
| 3 | Suspension | 20.4% | 6,190 |
| 4 | Other defects | 16.7% | 5,077 |
| 5 | Body, structure & corrosion | 10.3% | 3,148 |
| 6 | Lighting & signalling | 8.2% | 2,489 |
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 | 403 | 13.4% |
| 30-60k | 4,301 | 19.6% |
| 60-90k | 10,835 | 24.6% |
| 90-120k | 9,517 | 27.8% |
| 120-150k | 3,990 | 29.9% |
| 150k+ | 1,344 | 29.5% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 15,557 | 26.9% |
| Petrol | 14,852 | 24.4% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 6,609 | 24.2% |
| 2022 | 6,476 | 24.7% |
| 2023 | 6,250 | 26.1% |
| 2024 | 5,805 | 27.1% |
| 2025 | 5,269 | 26.6% |
What to check before buying a 2009 B-Class
Before buying a 2009 Mercedes-Benz B-Class, focus on the areas it most often fails on. Lighting & signalling accounted for 12.9% of tests for this year.
- Lighting & signalling (12.9% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (11.7% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
- Brakes (10.0% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
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 2009 Mercedes-Benz B-Classs pass their MOT?
74.3% of the 30,409 2009 Mercedes-Benz B-Class MOT tests in this dataset passed — a 25.7% fail rate.
What is the most common MOT failure on a 2009 Mercedes-Benz B-Class?
Lighting & signalling, recorded in 12.9% of tests, followed by suspension (11.7%).
Does the 2009 B-Class get worse with mileage?
Its MOT fail rate rises from 13.4% in the 0-30k band to 29.5% in the 150k+ band.
Methodology & source. Based on 30,409 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-01. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.