2004 Mercedes-Benz Cl — MOT failures & pass rate
Across 407 MOT tests, the 2004 Mercedes-Benz Cl recorded an 84.5% pass rate. Against coupes & convertibles of a similar age (22.5% fail rate), the 2004 Cl comes out 7.0pp better. Failures cluster in lighting & signalling, suspension and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (6.4%) and suspension (5.7%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are malfunction indicator lamp, service brake performance and rigid brake pipes — malfunction indicator lamp alone was recorded 16 times.
Mileage is the strongest signal on the record: 17.6% of 30-60k cars fail, rising to 10.3% once past 120-150k.
Advisories point at the next bill rather than this one: brakes was flagged on 27.5% of tests without failing them.
The trend is improving — the fail rate fell from 16.7% in 2021 to 10.1% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 6.4% | 26 |
| 2 | Suspension | 5.7% | 23 |
| 3 | Brakes | 5.4% | 22 |
| 4 | Emissions & environmental | 4.7% | 19 |
| 5 | Tyres | 3.7% | 15 |
| 6 | Visibility | 2.7% | 11 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Malfunction indicator lamp | 16 |
| 2 | Service brake performance | 15 |
| 3 | Rigid brake pipes | 13 |
| 4 | Shock absorbers | 10 |
| 5 | Ball joint | 10 |
| 6 | Headlamp aim | 9 |
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 | 27.5% | 112 |
| 2 | Suspension | 22.4% | 91 |
| 3 | Tyres | 19.9% | 81 |
| 4 | Emissions & environmental | 10.3% | 42 |
| 5 | Lighting & signalling | 7.4% | 30 |
| 6 | Body, structure & corrosion | 6.6% | 27 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 30-60k | 74 | 17.6% |
| 60-90k | 147 | 15.7% |
| 90-120k | 112 | 14.3% |
| 120-150k | 39 | 10.3% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 84 | 16.7% |
| 2022 | 93 | 16.1% |
| 2023 | 86 | 18.6% |
| 2024 | 75 | 14.7% |
| 2025 | 69 | 10.1% |
What to check before buying a 2004 Cl
On a 2004 Cl, lighting & signalling is what the MOT record says goes wrong most — it appeared in 6.4% of tests. Check these areas before you commit.
- Lighting & signalling (6.4% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (5.7% 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 (5.4% 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 Cls pass their MOT?
84.5% of the 407 2004 Mercedes-Benz Cl MOT tests in this dataset passed — a 15.5% fail rate.
What is the most common MOT failure on a 2004 Mercedes-Benz Cl?
Lighting & signalling, recorded in 6.4% of tests, followed by suspension (5.7%).
Does the 2004 Cl get worse with mileage?
Its MOT fail rate rises from 17.6% in the 30-60k band to 10.3% in the 120-150k band.
Methodology & source. Based on 407 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.