2004 Porsche Boxster — MOT failures & pass rate
The 2004 Porsche Boxster passed 81.4% of its 12,175 recorded MOT tests. That is 3.8 percentage points better than coupes & convertibles of a similar age, which fail at 22.5%. Failures cluster in lighting & signalling, emissions & environmental and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (9.3%) and emissions & environmental (7.6%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are catalyst emissions, rigid brake pipes and headlamp aim — catalyst emissions alone was recorded 858 times.
Mileage is the strongest signal on the record: 5.8% of 0-30k cars fail, rising to 28.6% once past 150k — 4.9× the risk.
Advisories point at the next bill rather than this one: brakes was flagged on 30.6% of tests without failing them.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 9.3% | 1,134 |
| 2 | Emissions & environmental | 7.6% | 927 |
| 3 | Brakes | 5.4% | 661 |
| 4 | Suspension | 4.6% | 560 |
| 5 | Tyres | 2.9% | 352 |
| 6 | Visibility | 2.7% | 324 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Catalyst emissions | 858 |
| 2 | Rigid brake pipes | 625 |
| 3 | Headlamp aim | 607 |
| 4 | Headlamp | 406 |
| 5 | Coil spring | 349 |
| 6 | Position lamp | 312 |
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 | 30.6% | 3,723 |
| 2 | Tyres | 17.6% | 2,138 |
| 3 | Suspension | 10.9% | 1,329 |
| 4 | Lighting & signalling | 8.8% | 1,074 |
| 5 | Emissions & environmental | 5.7% | 690 |
| 6 | Body, structure & corrosion | 5.0% | 603 |
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 | 549 | 5.8% |
| 30-60k | 2,855 | 12.4% |
| 60-90k | 4,854 | 18.6% |
| 90-120k | 2,801 | 23.7% |
| 120-150k | 885 | 28.2% |
| 150k+ | 224 | 28.6% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 2,550 | 18.4% |
| 2022 | 2,484 | 19.0% |
| 2023 | 2,483 | 19.0% |
| 2024 | 2,381 | 18.8% |
| 2025 | 2,277 | 17.9% |
What to check before buying a 2004 Boxster
On a 2004 Boxster, lighting & signalling is what the MOT record says goes wrong most — it appeared in 9.3% of tests. Check these areas before you commit.
- Lighting & signalling (9.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Emissions & environmental (7.6% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
- 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 Porsche Boxsters pass their MOT?
81.4% of the 12,175 2004 Porsche Boxster MOT tests in this dataset passed — a 18.6% fail rate.
What is the most common MOT failure on a 2004 Porsche Boxster?
Lighting & signalling, recorded in 9.3% of tests, followed by emissions & environmental (7.6%).
Does the 2004 Boxster get worse with mileage?
Its MOT fail rate rises from 5.8% in the 0-30k band to 28.6% in the 150k+ band.
Methodology & source. Based on 12,175 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.