2009 Mercedes-Benz S-Class — MOT failures & pass rate
The 2009 Mercedes-Benz S-Class passed 80.5% of its 5,478 recorded MOT tests. Against executive cars of a similar age (21.7% fail rate), the 2009 S-Class comes out 2.2pp better. Failures cluster in brakes, suspension and emissions & environmental.
What the MOT record shows
No single area dominates — brakes (8.5%) and suspension (7.2%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are ball joint, on or after 01/07/2008 and tread depth — ball joint alone was recorded 270 times.
Mileage matters less than usual here: the 2009 S-Class fails 16.9% of the time in the 0-30k band and 19.6% at 150k+, a spread of only 2.6 points.
Advisories point at the next bill rather than this one: brakes was flagged on 34.2% of tests without failing them.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Brakes | 8.5% | 467 |
| 2 | Suspension | 7.2% | 392 |
| 3 | Emissions & environmental | 6.4% | 350 |
| 4 | Lighting & signalling | 5.8% | 319 |
| 5 | Tyres | 5.1% | 281 |
| 6 | Visibility | 2.6% | 142 |
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 | 270 |
| 2 | On or after 01/07/2008 | 238 |
| 3 | Tread depth | 231 |
| 4 | Rbt (sp) | 211 |
| 5 | Rigid brake pipes | 206 |
| 6 | Pins and bushes | 139 |
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 | 34.2% | 1,872 |
| 2 | Tyres | 24.4% | 1,338 |
| 3 | Suspension | 20.3% | 1,113 |
| 4 | Emissions & environmental | 11.2% | 611 |
| 5 | Other defects | 4.9% | 268 |
| 6 | Body, structure & corrosion | 4.4% | 242 |
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 | 124 | 16.9% |
| 30-60k | 551 | 16.3% |
| 60-90k | 1,296 | 19.1% |
| 90-120k | 1,516 | 21.4% |
| 120-150k | 1,023 | 19.4% |
| 150k+ | 965 | 19.6% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 5,104 | 20.0% |
| Petrol | 374 | 13.4% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,260 | 19.9% |
| 2022 | 1,205 | 20.4% |
| 2023 | 1,127 | 18.5% |
| 2024 | 1,000 | 19.6% |
| 2025 | 886 | 19.0% |
What to check before buying a 2009 S-Class
On a 2009 S-Class, brakes is what the MOT record says goes wrong most — it appeared in 8.5% of tests. Check these areas before you commit.
- Brakes (8.5% 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.
- Suspension (7.2% 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.
- Emissions & environmental (6.4% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
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 2009 Mercedes-Benz S-Classs pass their MOT?
80.5% of the 5,478 2009 Mercedes-Benz S-Class MOT tests in this dataset passed — a 19.5% fail rate.
What is the most common MOT failure on a 2009 Mercedes-Benz S-Class?
Brakes, recorded in 8.5% of tests, followed by suspension (7.2%).
Does the 2009 S-Class get worse with mileage?
Its MOT fail rate rises from 16.9% in the 0-30k band to 19.6% in the 150k+ band.
Methodology & source. Based on 5,478 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.