2025 MOT results
Mercedes-Benz GLB-Class common problems
The most common reason a Mercedes-Benz GLB-Class fails its MOT is a cut tyre, on 24.0% of its 1,202 failed tests in 2025. Against other cars of the same age, 4 faults stand out, the widest gaps being: a horn not working at 3.2% of failures against 0.3% expected; a braking fault at 5.0% of failures against 0.9% expected; the airbag light on at 2.8% of failures against 0.8% expected.
- Tests in 2025 11,929 Cars aged three and over
- Failed first time 10.1% 1,202 tests
- Found a dangerous defect 3.2% Unsafe to drive away
- Ended with an advisory 32.9% A problem to watch, not a failure
What fails a Mercedes-Benz GLB-Class MOT
Each bar is the share of failed Mercedes-Benz GLB-Class tests with that defect. Where we can compare it with cars of the same registration years, the marker shows what an average car of those ages records (12 of the 12 items below).
Most common reasons for failure
A test can fail for more than one defect, so shares add up to more than 100%.
| Defect | Share of failed tests |
|---|---|
| Tyres: cut in excess of the requirements deep enough to reach the ply or cords Tyres | 24.0% |
| Brake pads: less than 1.5 mm thick Brakes | 11.0% |
| Tyres: ply or cords exposed Tyres | 9.1% |
| Tyres: tread depth below requirements of 1.6mm Tyres | 8.6% |
| Wipers: does not clear the windscreen effectively Visibility | 8.0% |
| Headlamp aim: too high Lamps, reflectors and electrical equipment | 6.2% |
| Brake pads: worn down to wear indicator Brakes | 5.0% |
| Headlamp aim: too low Lamps, reflectors and electrical equipment | 3.6% |
| Horn: not working Lamps, reflectors and electrical equipment | 3.2% |
| Registration plates: does not conform to the specified requirements Identification of the vehicle | 3.1% |
| SRS malfunction indicator lamp: warning lamp indicates a fault Seat belts and supplementary restraint systems | 2.8% |
| Tyres: bulge, caused by separation or partial failure of its structure Tyres | 2.4% |
Source:DVSA,UK Motoring analysis 2025 Updated
-
Cut tyre
24.0% of failures 17.0% expected somewhat more often
A cut in the tyre deep or long enough to reach the structure underneath, usually from a kerb or debris.
Run a hand round the inner and outer walls of each tyre, which is where kerbing shows.
-
Worn brake pads
11.0% of failures 7.6% expected somewhat more often
Friction material worn under 1.5mm, thinner than the point most manufacturers call the limit.
Look through the wheel spokes at the pad against the disc; wear indicators squeal before they get this far.
-
Tyre worn through to the cords
9.1% of failures 9.1% expected about as expected
The tyre is worn or damaged far enough to expose the cords underneath, which is a dangerous defect.
Run a hand round the inner and outer walls of each tyre, which is where kerbing shows.
-
Tyre worn below the legal limit
8.6% of failures 11.0% expected somewhat less often
A tyre worn past the 1.6mm legal minimum across the middle three quarters of the tread.
A 20p coin in the main grooves: if the outer band of the coin is visible, the tyre is close to the limit.
-
Wiper blades that do not clear the screen
8.0% of failures 15.3% expected 2 times less often
Wiper blades that leave the windscreen smeared or streaked across the area the driver looks through.
Look for split or hardened rubber, and lift each blade to see whether it still sits flat.
-
Headlamp aim set too high
6.2% of failures 5.5% expected about as expected
The dipped beam points higher than it should, which dazzles oncoming drivers.
Nothing to do at the roadside, but a garage resets the aim in minutes; a sagging suspension corner or a heavy boot load can throw it out.
Which parts of the car fail
Tyres is the area that most often fails a Mercedes-Benz GLB-Class, on 46.0% of failed tests. The widest gap against cars of the same registration years is brakes, on 19.1% against 13.3% expected.
Failure categories
DVSA's own sections of the test. The marker is what cars of the same registration years record.
| Defect category | Share of failed tests |
|---|---|
| Tyres | 46.0% |
| Brakes | 19.1% |
| Lamps, reflectors and electrical equipment | 16.1% |
| Visibility | 12.5% |
| Suspension | 5.5% |
| Seat belts and supplementary restraint systems | 5.0% |
| Identification of the vehicle | 3.2% |
| Noise, emissions and leaks | 2.1% |
Source:DVSA,UK Motoring analysis 2025 Updated
What testers warn about
32.9% of Mercedes-Benz GLB-Class tests ended with at least one advisory: a fault the tester found that did not fail the test. On Mercedes-Benz GLB-Classes, these are the items to ask about on a car you are viewing, because they are what the last tester expected to go next.
Most common advisories
Share of all tests, passes included.
| Advisory | Share of tests |
|---|---|
| Tread depth: worn close to legal limit or worn on edge Tyres | 12.8% |
| Brake pads: wearing thin Brakes | 8.3% |
| Tyres: slightly damaged or cracking or perishing Tyres | 7.5% |
| Child seat fitted not allowing full inspection of adult belt Non-component advisories | 4.8% |
| Brake discs: worn, but not excessively Brakes | 3.4% |
| Brake discs: worn, pitted or scored, but not seriously weakened Brakes | 2.9% |
| Nail in tyre Non-component advisories | 2.8% |
| Tyres: cut but not deep enough to reach the ply or cords Tyres | 2.5% |
| Linkage ball joint has slight play Suspension | 0.9% |
| Items removed from driver's view prior to test Non-component advisories | 0.6% |
| Tyres: slightly damaged Tyres | 0.6% |
| Registration plates: deteriorated but not likely to be misread Identification of the vehicle | 0.5% |
Source:DVSA,UK Motoring analysis 2025 Updated
Mercedes-Benz GLB-Class problems: common questions
What is the most common problem with a Mercedes-Benz GLB-Class?
Of the faults that fail an MOT, “Tyres: cut in excess of the requirements deep enough to reach the ply or cords” is the most common: it appears on 24.0% of failed Mercedes-Benz GLB-Class tests. Across categories, tyres is the area that most often fails one, on 46.0% of failed tests.
How often does a Mercedes-Benz GLB-Class fail its MOT?
10.1% of Mercedes-Benz GLB-Class tests in 2025 were not passed first time, from 11,929 tests of cars aged three and over. Allowing for the age and mileage of the cars tested, that gives it a UK Motoring Reliability Score of 58 out of 100, where 50 is as expected.
Does anything fail more often on a Mercedes-Benz GLB-Class than on other cars?
Yes. “Horn: not working” appears on 3.2% of its failures against 0.3% for cars of the same age, and “Brake pads: worn down to wear indicator” appears on 5.0% of its failures against 0.9% for cars of the same age. Where an item is missing from the national figures for a year, we use the smallest share those figures show, so the comparison never overstates the difference.
Are these the same as breakdowns or known faults?
No. These are the items a tester recorded at the MOT, which covers condition and safety: lamps, brakes, tyres, suspension, corrosion and emissions. A gearbox that is unpleasant, an infotainment screen that has died, or a car that will not start on a cold morning are not part of the test, so they are not in these figures.
Where do the figures come from?
Every normal MOT test of a Mercedes-Benz GLB-Class aged three and over in Great Britain in 2025, from DVSA's anonymised MOT results. Retests are excluded, and the same fault on more than one wheel counts once.
Data stories to read next
Data sources and methodology
| Figures | Source | Period | Records | Updated |
|---|---|---|---|---|
| MOT defects and advisories | Anonymised MOT tests and results Driver and Vehicle Standards Agency Derived statistics UK Motoring | 2025 | 11,929 MOT tests | 19 September 2026 |
- Shares for defects are of failed tests; shares for advisories are of all tests. A test can carry several defects, so shares add to more than 100%.
- The expected share is what an average car of the same registration years records, weighted by where this model’s failures fall. Where an item is outside the national figures for a year, the smallest share those figures show is used in its place, which is an upper bound, so the comparison never overstates a model’s problems. No expectation is published where less than 80% of the model’s failures can be compared.
- Great Britain only: DVSA does not run MOT testing in Northern Ireland. Cars under three years old are not tested.
- The descriptions of what each part does are general and the same on every model. Every figure comes from the MOT data.
Contains public sector information licensed under the Open Government Licence v3.0.