2005 Porsche 911 — MOT failures & pass rate
Across 15,369 MOT tests, the 2005 Porsche 911 recorded an 88.8% pass rate. Coupes & convertibles of a similar age fail 22.3% of the time, so this is 11.1pp better than the group it competes with. Failures cluster in lighting & signalling, emissions & environmental and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (4.4%) and emissions & environmental (3.1%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, catalyst emissions and rigid brake pipes — headlamp aim alone was recorded 546 times.
A 150k+ example is materially riskier than a 0-30k one: 23.0% versus 4.4%.
Brakes is the most common advisory, noted on 20.2% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 4.4% | 671 |
| 2 | Emissions & environmental | 3.1% | 477 |
| 3 | Brakes | 2.6% | 405 |
| 4 | Tyres | 2.5% | 387 |
| 5 | Suspension | 2.1% | 327 |
| 6 | Body, structure & corrosion | 1.4% | 210 |
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 | 546 |
| 2 | Catalyst emissions | 448 |
| 3 | Rigid brake pipes | 371 |
| 4 | Tread depth | 172 |
| 5 | Coil spring | 148 |
| 6 | Registration plates | 141 |
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 | 20.2% | 3,107 |
| 2 | Tyres | 14.6% | 2,239 |
| 3 | Suspension | 8.1% | 1,237 |
| 4 | Other defects | 5.7% | 878 |
| 5 | Lighting & signalling | 4.9% | 750 |
| 6 | Emissions & environmental | 3.8% | 578 |
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 | 927 | 4.4% |
| 30-60k | 4,676 | 8.1% |
| 60-90k | 6,415 | 11.9% |
| 90-120k | 2,679 | 15.8% |
| 120-150k | 517 | 15.9% |
| 150k+ | 152 | 23.0% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,172 | 10.9% |
| 2022 | 3,102 | 10.9% |
| 2023 | 3,108 | 11.3% |
| 2024 | 3,028 | 12.1% |
| 2025 | 2,959 | 10.8% |
What to check before buying a 2005 911
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 4.4% of tests. Start there.
- Lighting & signalling (4.4% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Emissions & environmental (3.1% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
- Brakes (2.6% 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 2005 Porsche 911s pass their MOT?
88.8% of the 15,369 2005 Porsche 911 MOT tests in this dataset passed — a 11.2% fail rate.
What is the most common MOT failure on a 2005 Porsche 911?
Lighting & signalling, recorded in 4.4% of tests, followed by emissions & environmental (3.1%).
Does the 2005 911 get worse with mileage?
Its MOT fail rate rises from 4.4% in the 0-30k band to 23.0% in the 150k+ band.
Methodology & source. Based on 15,369 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.