Mercedes-Benz B-Class MOT pass rate and common problems
79.0% of 110,551 Mercedes-Benz B-Class MOT tests pass.
At 79.0%, the B-Class passes slightly less often than the average across all Mercedes-Benz models (83.5%).
The Mercedes-Benz B-Class's pass rate of 79.0% is in line with the national average for cars, at 79.2%.
Own this Mercedes-Benz B-Class?
This is the average across every Mercedes-Benz B-Class in the dataset. Look up your own registration for its actual MOT history, and a free place to keep its maintenance records.
Have service invoices? Upload and keep them with your car’s history →
How to check and keep your Mercedes-Benz’s service history →
Pass rate by vehicle age
Pass rate drops sharply with age: the Mercedes-Benz B-Class tested at 0–3 years pass 94.2% of the time, compared with just 64.3% at 15+ years.
| Vehicle age | Pass rate | Tests | Average mileage |
|---|---|---|---|
| 0–3 years | 94.2% | 2,831 | 23,121 miles |
| 3–6 years | 92.6% | 16,906 | 29,753 miles |
| 6–10 years | 84.9% | 33,810 | 56,763 miles |
| 10–15 years | 73.3% | 41,423 | 81,860 miles |
| 15+ years | 64.3% | 15,581 | 100,481 miles |
Common MOT failure reasons for the Mercedes-Benz B-Class
The most common reason the Mercedes-Benz B-Class fails its MOT is lamps, reflectors and electrical equipment — present in 42.6% of failed tests, most often logged as "Not working".
| Category | Share of failed tests | Example |
|---|---|---|
| Lamps, reflectors and electrical equipment | 42.6% | Not working |
| Suspension | 36.3% | Ball joint dust cover no longer prevents the ingress of dirt |
| Brakes | 31.0% | Excessively corroded |
| Tyres | 26.4% | Has a cut in excess of the requirements deep enough to reach the ply or cords |
| Visibility | 13.9% | Provides insufficient washer liquid |
| Body, chassis, structure | 11.3% | Constant velocity boot split or insecure, no longer prevents the ingress of dirt |
| Noise, emissions and leaks | 9.6% | Inoperative or indicates a malfunction |
| Seat belts and supplementary restraint systems | 4.4% | Warning lamp indicates a fault |
| Road Wheels | 2.9% | Fixing missing |
| Steering | 1.5% | Ball joint has excessive play |
Buying a used Mercedes-Benz B-Class: what to check
These checks follow the Mercedes-Benz B-Class’s own MOT record: the areas it fails on most often, and how that changes as the car gets older. None of them replaces a mechanic’s inspection, but they tell you where to look first.
The biggest drop in pass rate for the Mercedes-Benz B-Class comes between 6–10 years and 10–15 years old, from 84.9% to 73.3%. If you are looking at one in or just past that range, read its MOT history closely.
By mileage, the steepest fall is from 30,000–60,000 mi to 60,000–90,000 mi: 85.7% down to 74.9%. Mileage matters as well as age, so compare the car’s recorded mileages with its year.
1. Lights and electrics
Recorded in 42.6% of failed Mercedes-Benz B-Class MOTs. 21.7% of tests at 15+ years failed on lights and electrics, against 1.5% at 0–3 years.
Walk round with the lights on: headlights (dipped and main), indicators, brake lights, fog light and number-plate lamp. Check the dashboard warning lights come on with the ignition, then go out once the engine starts.
2. Suspension
Recorded in 36.3% of failed Mercedes-Benz B-Class MOTs. Rare on young cars, but 20.0% of tests at 15+ years failed on suspension.
Listen for knocks over bumps and speed humps, and check the car sits level. Push down on each corner: it should settle rather than keep bouncing.
3. Brakes
Recorded in 31.0% of failed Mercedes-Benz B-Class MOTs. Rare on young cars, but 22.6% of tests at 15+ years failed on brakes.
On the test drive, the car should stop straight without pulling or juddering, and the handbrake should hold it on a slope. Look through the wheels for scored or heavily lipped discs.
4. Tyres
Recorded in 26.4% of failed Mercedes-Benz B-Class MOTs.
Check tread depth across the whole width of every tyre, including the inner edge. Uneven wear can point to alignment or suspension problems. Look for cuts and bulges in the sidewalls.
5. Windscreen and wipers
Recorded in 13.9% of failed Mercedes-Benz B-Class MOTs. 8.9% of tests at 15+ years failed on windscreen and wipers, against 1.6% at 0–3 years.
Look for windscreen chips and cracks in the driver’s line of sight, and check the wipers clear the screen and the washers work.
Check the car’s own MOT history. Averages describe the model, not the car in front of you. Look up its registration for past failures, advisories that were never fixed, and gaps or dips in the recorded mileage.
Ask for the service history. Invoices show what was done and when; a stamp alone shows less. See how to check Mercedes-Benz service history and what a service history check can tell you.
Related Mercedes-Benz models
- Mercedes-Benz GLC — 91.1% pass rate
- Mercedes-Benz Cla — 87.2% pass rate
- Mercedes-Benz Vito — 75.2% pass rate
- Mercedes-Benz SLK — 78.9% pass rate
- Mercedes-Benz Gle — 91.9% pass rate
- Mercedes-Benz ML — 80.7% pass rate
Frequently asked questions
- What is the MOT pass rate for the Mercedes-Benz B-Class?
- 79.0% of Mercedes-Benz B-Class MOT tests pass, based on 110,551 tests in the DVSA anonymised MOT tests and results dataset.
- What are the most common MOT failures for the Mercedes-Benz B-Class?
- The most common reason the Mercedes-Benz B-Class fails its MOT is lamps, reflectors and electrical equipment — present in 42.6% of failed tests, most often logged as "Not working".
- What are the common problems with the Mercedes-Benz B-Class?
- Going by its MOT results, the most common problem areas on the Mercedes-Benz B-Class are lights and electrics; suspension; brakes. 21.7% of tests at 15+ years failed on lights and electrics, against 1.5% at 0–3 years.
- What should I check when buying a used Mercedes-Benz B-Class?
- Start with the areas it most often fails its MOT on: lights and electrics; suspension; brakes; tyres; windscreen and wipers. Then check the specific car's MOT history by registration for failures, advisories and mileage, and ask the seller for service invoices.
- Does this show the Mercedes-Benz B-Class's service history?
- No — this is MOT test data, which covers roadworthiness, not servicing. A service history is a separate record of maintenance work, which a specific car only has if its owner has kept it. See the Mercedes-Benz service history guide for how to check and keep one.