2004 Mercedes-Benz A-Class — MOT failures & pass rate
Across 11,021 MOT tests analysed for the 2004 Mercedes-Benz A-Class, the most common recorded failure areas were lighting & signalling, suspension and brakes. Its pass rate of 71.8% was in line with the average for small family cars of a similar age (71.9%). Higher-mileage examples failed more often — 36.6% in the 150k+ group versus 24.2% in the 0-30k group.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 18.4% | 2,028 |
| 2 | Suspension | 13.6% | 1,495 |
| 3 | Brakes | 10.4% | 1,149 |
| 4 | Visibility | 8.6% | 948 |
| 5 | Tyres | 5.8% | 641 |
| 6 | Emissions & environmental | 4.7% | 519 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Headlamp aim | 866 |
| 2 | Rigid brake pipes | 812 |
| 3 | Coil spring | 733 |
| 4 | Stop lamp | 671 |
| 5 | Headlamp | 603 |
| 6 | Washers | 563 |
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 | 46.0% | 5,073 |
| 2 | Suspension | 31.4% | 3,455 |
| 3 | Tyres | 27.6% | 3,038 |
| 4 | Other defects | 19.2% | 2,114 |
| 5 | Lighting & signalling | 18.0% | 1,985 |
| 6 | Body, structure & corrosion | 10.4% | 1,143 |
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 | 389 | 24.2% |
| 30-60k | 2,190 | 22.3% |
| 60-90k | 4,157 | 27.3% |
| 90-120k | 2,746 | 31.3% |
| 120-150k | 829 | 33.3% |
| 150k+ | 216 | 36.6% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 9,626 | 27.9% |
| Diesel | 1,395 | 30.5% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,533 | 30.3% |
| 2022 | 2,682 | 27.8% |
| 2023 | 2,073 | 27.3% |
| 2024 | 1,594 | 26.7% |
| 2025 | 1,139 | 26.6% |
What to check before buying a 2004 A-Class
Before buying a 2004 Mercedes-Benz A-Class, focus on the areas it most often fails on. Lighting & signalling accounted for 18.4% of tests for this year.
- Lighting & signalling (18.4% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (13.6% 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 (10.4% 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 A-Classs pass their MOT?
71.8% of the 11,021 2004 Mercedes-Benz A-Class MOT tests in this dataset passed — a 28.2% fail rate.
What is the most common MOT failure on a 2004 Mercedes-Benz A-Class?
Lighting & signalling, recorded in 18.4% of tests, followed by suspension (13.6%).
Does the 2004 A-Class get worse with mileage?
Its MOT fail rate rises from 24.2% in the 0-30k band to 36.6% in the 150k+ band.
Methodology & source. Based on 11,021 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-01. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.