2003 Mercedes-Benz S-Class — MOT failures & pass rate
The 2003 Mercedes-Benz S-Class passed 80.8% of its 4,612 recorded MOT tests. Against executive cars of a similar age (24.4% fail rate), the 2003 S-Class comes out 5.1pp better. Failures cluster in lighting & signalling, suspension and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (10.3%) and suspension (8.4%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are ball joint, headlamp and tread depth — ball joint alone was recorded 237 times.
A 150k+ example is materially riskier than a 0-30k one: 21.5% versus 10.0%.
Split by fuel, diesel examples fail 3.8pp more often than petrol ones (21.3% vs 17.5%) — worth weighing if you have a choice.
Advisories point at the next bill rather than this one: brakes was flagged on 34.5% of tests without failing them.
The trend is improving — the fail rate fell from 21.3% in 2021 to 18.8% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 10.3% | 474 |
| 2 | Suspension | 8.4% | 386 |
| 3 | Brakes | 5.9% | 271 |
| 4 | Tyres | 5.4% | 250 |
| 5 | Seat belts & restraints | 3.5% | 161 |
| 6 | Visibility | 3.2% | 148 |
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 | 237 |
| 2 | Headlamp | 204 |
| 3 | Tread depth | 193 |
| 4 | Headlamp aim | 192 |
| 5 | Pins and bushes | 166 |
| 6 | Rigid brake pipes | 157 |
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 | 34.5% | 1,592 |
| 2 | Suspension | 26.9% | 1,241 |
| 3 | Tyres | 24.1% | 1,113 |
| 4 | Lighting & signalling | 12.5% | 576 |
| 5 | Other defects | 11.5% | 531 |
| 6 | Emissions & environmental | 9.9% | 458 |
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 | 100 | 10.0% |
| 30-60k | 325 | 15.1% |
| 60-90k | 814 | 14.1% |
| 90-120k | 1,066 | 18.5% |
| 120-150k | 1,018 | 22.8% |
| 150k+ | 1,221 | 21.5% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 2,508 | 17.5% |
| Diesel | 2,104 | 21.3% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,278 | 21.3% |
| 2022 | 1,085 | 19.0% |
| 2023 | 923 | 17.7% |
| 2024 | 721 | 18.4% |
| 2025 | 605 | 18.8% |
What to check before buying a 2003 S-Class
On a 2003 S-Class, lighting & signalling is what the MOT record says goes wrong most — it appeared in 10.3% of tests. Check these areas before you commit.
- Lighting & signalling (10.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (8.4% 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 (5.9% 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 2003 Mercedes-Benz S-Classs pass their MOT?
80.8% of the 4,612 2003 Mercedes-Benz S-Class MOT tests in this dataset passed — a 19.3% fail rate.
What is the most common MOT failure on a 2003 Mercedes-Benz S-Class?
Lighting & signalling, recorded in 10.3% of tests, followed by suspension (8.4%).
Does the 2003 S-Class get worse with mileage?
Its MOT fail rate rises from 10.0% in the 0-30k band to 21.5% in the 150k+ band.
Methodology & source. Based on 4,612 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.