2004 Mercedes-Benz S-Class — MOT failures & pass rate
4,368 MOT tests on the 2004 Mercedes-Benz S-Class are in this dataset, and 82.2% of them passed. Executive cars of a similar age fail 24.3% of the time, so this is 6.6pp better than the group it competes with. Failures cluster in lighting & signalling, suspension and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (10.1%) and suspension (7.9%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are ball joint, headlamp aim and headlamp — ball joint alone was recorded 244 times.
Mileage is the strongest signal on the record: 5.0% of 0-30k cars fail, rising to 20.3% once past 150k — 4.1× the risk.
The petrol cars hold up better: 15.2% fail against 20.3% for diesel, a 5.1-point gap across 4,367 tests.
Brakes is the most common advisory, noted on 34.0% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 19.0% in 2021 to 16.1% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 10.1% | 443 |
| 2 | Suspension | 7.9% | 347 |
| 3 | Brakes | 6.3% | 274 |
| 4 | Tyres | 4.5% | 197 |
| 5 | Visibility | 3.1% | 134 |
| 6 | Seat belts & restraints | 2.7% | 118 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Ball joint | 244 |
| 2 | Headlamp aim | 180 |
| 3 | Headlamp | 180 |
| 4 | Rigid brake pipes | 172 |
| 5 | Tread depth | 157 |
| 6 | Pins and bushes | 151 |
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 | 34.0% | 1,487 |
| 2 | Tyres | 24.3% | 1,060 |
| 3 | Suspension | 23.4% | 1,024 |
| 4 | Lighting & signalling | 12.3% | 537 |
| 5 | Emissions & environmental | 10.4% | 455 |
| 6 | Other defects | 10.3% | 452 |
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 | 101 | 5.0% |
| 30-60k | 295 | 10.5% |
| 60-90k | 775 | 16.5% |
| 90-120k | 976 | 18.6% |
| 120-150k | 979 | 18.5% |
| 150k+ | 1,200 | 20.3% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 2,187 | 20.3% |
| Petrol | 2,180 | 15.2% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,172 | 19.0% |
| 2022 | 1,009 | 18.0% |
| 2023 | 855 | 18.1% |
| 2024 | 724 | 16.4% |
| 2025 | 608 | 16.1% |
What to check before buying a 2004 S-Class
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 10.1% of tests. Start there.
- Lighting & signalling (10.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (7.9% 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 (6.3% 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 2004 Mercedes-Benz S-Classs pass their MOT?
82.2% of the 4,368 2004 Mercedes-Benz S-Class MOT tests in this dataset passed — a 17.8% fail rate.
What is the most common MOT failure on a 2004 Mercedes-Benz S-Class?
Lighting & signalling, recorded in 10.1% of tests, followed by suspension (7.9%).
Does the 2004 S-Class get worse with mileage?
Its MOT fail rate rises from 5.0% in the 0-30k band to 20.3% in the 150k+ band.
Methodology & source. Based on 4,368 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.