2025 MOT results
Mercedes-Benz S-Class common problems
The most common reason a Mercedes-Benz S-Class fails its MOT is a worn steering or suspension joint, on 16.6% of its 4,216 failed tests in 2025. Against other cars of the same age, 5 faults stand out, the widest gaps being: a worn steering or suspension joint at 16.6% of failures against 5.0% expected; a split joint boot at 4.0% of failures against 2.0% expected; corroded brake pipes at 3.8% of failures against 2.0% expected.
- Tests in 2025 25,742 Cars aged three and over
- Failed first time 16.4% 4,216 tests
- Found a dangerous defect 5.7% Unsafe to drive away
- Ended with an advisory 40.2% A problem to watch, not a failure
What fails a Mercedes-Benz S-Class MOT
Each bar is the share of failed Mercedes-Benz S-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 |
|---|---|
| Suspension arms: ball joint excessively worn Suspension | 16.6% |
| Tyres: tread depth below requirements of 1.6mm Tyres | 10.3% |
| Malfunction indicator lamp: inoperative or indicates a malfunction Noise, emissions and leaks | 10.2% |
| Tyres: ply or cords exposed Tyres | 7.4% |
| Tyres: cut in excess of the requirements deep enough to reach the ply or cords Tyres | 6.5% |
| Parking brake efficiency below requirements Brakes | 5.1% |
| Washers: provides insufficient washer liquid Visibility | 5.1% |
| Suspension arms: pin or bush excessively worn Suspension | 4.6% |
| Wipers: does not clear the windscreen effectively Visibility | 4.6% |
| Brake pads: less than 1.5 mm thick Brakes | 4.5% |
| Suspension arms: ball joint dust cover no longer prevents the ingress of dirt Suspension | 4.0% |
| Rigid brake pipes: excessively corroded Brakes | 3.8% |
Source:DVSA,UK Motoring analysis 2025 Updated
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Worn steering or suspension joint
16.6% of failures 5.0% expected 3.3 times as often
Play in a steering or suspension joint, where a worn ball and socket lets the wheel move where it should not.
A knock at low speed over rough ground, or vague steering, is the usual warning.
-
Tyre worn below the legal limit
10.3% of failures 7.8% expected somewhat more 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.
-
Engine management light on
10.2% of failures 5.4% expected 1.9 times as often
The engine management light is on, or has been disconnected. Either fails the test.
A cheap code reader on the diagnostic socket will say what the car has stored before you pay for a test.
-
Tyre worn through to the cords
7.4% of failures 4.7% expected 1.6 times as often
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.
-
Cut tyre
6.5% of failures 4.8% 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.
-
Weak handbrake
5.1% of failures 4.2% expected somewhat more often
The handbrake cannot hold the car to the efficiency the test requires, usually from a stretched cable or seized rear callipers.
On a hill, the handbrake should hold the car with a couple of clicks left in the lever.
Which parts of the car fail
Tyres is the area that most often fails a Mercedes-Benz S-Class, on 29.9% of failed tests. That is also where it differs most from cars of the same registration years, which record 22.2%.
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 | 29.9% |
| Suspension | 29.3% |
| Brakes | 23.9% |
| Lamps, reflectors and electrical equipment | 21.3% |
| Noise, emissions and leaks | 16.1% |
| Visibility | 14.4% |
| Body, chassis, structure | 5.1% |
| Seat belts and supplementary restraint systems | 5.0% |
Source:DVSA,UK Motoring analysis 2025 Updated
What testers warn about
40.2% of Mercedes-Benz S-Class tests ended with at least one advisory: a fault the tester found that did not fail the test. On Mercedes-Benz S-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 | 15.9% |
| Brake discs: worn, pitted or scored, but not seriously weakened Brakes | 7.2% |
| Rigid brake pipes: corroded, covered in grease or other material Brakes | 6.0% |
| Brake pads: wearing thin Brakes | 5.9% |
| Suspension arms: ball joint has slight play Suspension | 5.9% |
| Engine oil leak, but not excessive Noise, emissions and leaks | 5.5% |
| Tyres: slightly damaged or cracking or perishing Tyres | 3.1% |
| Brake discs: worn, but not excessively Brakes | 3.1% |
| Wheel bearings: slight play Suspension | 2.6% |
| Suspension arms: pin or bush worn but not resulting in excessive movement Suspension | 2.0% |
| Tyres: cut but not deep enough to reach the ply or cords Tyres | 1.7% |
| Play in steering rack inner joint(s) Non-component advisories | 1.3% |
Source:DVSA,UK Motoring analysis 2025 Updated
Mercedes-Benz S-Class problems: common questions
What is the most common problem with a Mercedes-Benz S-Class?
Of the faults that fail an MOT, “Suspension arms: ball joint excessively worn” is the most common: it appears on 16.6% of failed Mercedes-Benz S-Class tests. Across categories, tyres is the area that most often fails one, on 29.9% of failed tests.
How often does a Mercedes-Benz S-Class fail its MOT?
16.4% of Mercedes-Benz S-Class tests in 2025 were not passed first time, from 25,742 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 69 out of 100, where 50 is as expected.
Does anything fail more often on a Mercedes-Benz S-Class than on other cars?
Yes. “Suspension arms: ball joint excessively worn” appears on 16.6% of its failures against 5.0% for cars of the same age, and “Suspension arms: ball joint dust cover no longer prevents the ingress of dirt” appears on 4.0% of its failures against 2.0% 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 S-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 | 25,742 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.