Mercedes-Benz GLB MOT pass rate & common failures
23,180 MOT tests on the Mercedes-Benz GLB (2018–2025) give it a 92.4% pass rate. That is effectively the same as mid-size SUVs of a similar age (8.2% fail rate), so the MOT record here is unremarkable in either direction. Its most common failure areas are tyres, brakes and lighting & signalling.
What the MOT record shows
No single area dominates — tyres (4.5%) and brakes (1.5%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are brake pads, headlamp aim and tread depth — brake pads alone was recorded 353 times.
A 90-120k example is materially riskier than a 0-30k one: 12.6% versus 5.7%.
Fuel type barely separates them — petrol fails 7.1% of the time against 8.1% for diesel.
Advisories point at the next bill rather than this one: tyres was flagged on 20.2% of tests without failing them.
The trend is worsening — 4.1% of tests failed in 2022 against 7.8% in 2025, the usual pattern as a fleet ages.
How it compares
By model year
Every GLB model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 2020 | 8,362 | 91.3% | 8.6% | Tyres |
| 2021 | 8,706 | 92.5% | 7.5% | Tyres |
| 2022 | 5,762 | 93.3% | 6.7% | Tyres |
| 2023 | 316 | 96.8% | 3.2% | Tyres |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.5% | 1,033 |
| 2 | Brakes | 1.5% | 349 |
| 3 | Lighting & signalling | 1.4% | 328 |
| 4 | Visibility | 1.2% | 272 |
| 5 | Seat belts & restraints | 0.5% | 122 |
| 6 | Suspension | 0.5% | 107 |
| 7 | Other defects | 0.3% | 64 |
| 8 | Emissions & environmental | 0.2% | 48 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Brake pads | 353 |
| 2 | Headlamp aim | 327 |
| 3 | Tread depth | 290 |
| 4 | Wipers | 201 |
| 5 | Registration plates | 107 |
| 6 | Washers | 69 |
| 7 | SRS malfunction indicator lamp | 65 |
| 8 | Brake discs | 62 |
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 | 20.2% | 4,687 |
| 2 | Brakes | 11.1% | 2,575 |
| 3 | Other defects | 8.3% | 1,934 |
| 4 | Visibility | 3.3% | 755 |
| 5 | Suspension | 1.3% | 293 |
| 6 | Seat belts & restraints | 0.4% | 83 |
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 | 11,465 | 5.7% |
| 30-60k | 10,480 | 9.2% |
| 60-90k | 1,078 | 11.6% |
| 90-120k | 135 | 12.6% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 11,986 | 8.1% |
| Petrol | 11,175 | 7.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2022 | 49 | 4.1% |
| 2023 | 2,991 | 7.8% |
| 2024 | 7,253 | 7.3% |
| 2025 | 12,885 | 7.8% |
What to check before buying a Mercedes-Benz GLB
- Tyres (4.5% 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.
- Brakes (1.5% 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.
- Lighting & signalling (1.4% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
What is the MOT pass rate for the Mercedes-Benz GLB?
92.4% of the 23,180 Mercedes-Benz GLB MOT tests in this dataset passed, a 7.6% fail rate, across model years 2018–2025.
What does the Mercedes-Benz GLB most often fail its MOT on?
Tyres, recorded in 4.5% of tests, then brakes (1.5%).
How much does mileage affect GLB MOT results?
Fail rates run at 5.7% for cars in the 0-30k band and 12.6% for 90-120k, a 6.9-point difference.
Is the petrol or diesel GLB more reliable at MOT time?
On MOT-testable defects the petrol fails 7.1% of the time against 8.1% for the diesel. This covers testable items only, not engine or gearbox reliability.
Methodology & source. Based on 23,180 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.