2017 Porsche 911 — MOT failures & pass rate
Across 9,975 MOT tests, the 2017 Porsche 911 recorded a 95.5% pass rate. Against coupes & convertibles of a similar age (9.8% fail rate), the 2017 911 comes out 5.3pp better. Failures cluster in tyres, lighting & signalling and other defects.
What the MOT record shows
No single area dominates — tyres (2.7%) and lighting & signalling (1.1%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, registration plates and tread depth — headlamp aim alone was recorded 115 times.
Mileage is the strongest signal on the record: 3.8% of 0-30k cars fail, rising to 10.8% once past 60-90k — 2.9× the risk.
Advisories point at the next bill rather than this one: tyres was flagged on 12.1% of tests without failing them.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 2.7% | 269 |
| 2 | Lighting & signalling | 1.1% | 109 |
| 3 | Other defects | 0.7% | 68 |
| 4 | Visibility | 0.6% | 57 |
| 5 | Brakes | 0.3% | 33 |
| 6 | Suspension | 0.3% | 32 |
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 | 115 |
| 2 | Registration plates | 103 |
| 3 | Tread depth | 95 |
| 4 | Washers | 50 |
| 5 | Headlamp cleaning device | 30 |
| 6 | Coil spring | 21 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Tyres | 12.1% | 1,207 |
| 2 | Other defects | 2.9% | 290 |
| 3 | Brakes | 2.2% | 216 |
| 4 | Visibility | 1.2% | 123 |
| 5 | Suspension | 0.8% | 82 |
| 6 | Emissions & environmental | 0.5% | 46 |
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 | 7,707 | 3.8% |
| 30-60k | 2,112 | 6.6% |
| 60-90k | 120 | 10.8% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 2,100 | 4.2% |
| 2022 | 2,036 | 4.2% |
| 2023 | 2,006 | 4.4% |
| 2024 | 1,891 | 4.9% |
| 2025 | 1,942 | 5.0% |
What to check before buying a 2017 911
On a 2017 911, tyres is what the MOT record says goes wrong most — it appeared in 2.7% of tests. Check these areas before you commit.
- Tyres (2.7% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Lighting & signalling (1.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Other defects (0.7% of tests): Miscellaneous items not in the main categories. Typical repair: varies.
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 2017 Porsche 911s pass their MOT?
95.5% of the 9,975 2017 Porsche 911 MOT tests in this dataset passed — a 4.5% fail rate.
What is the most common MOT failure on a 2017 Porsche 911?
Tyres, recorded in 2.7% of tests, followed by lighting & signalling (1.1%).
Does the 2017 911 get worse with mileage?
Its MOT fail rate rises from 3.8% in the 0-30k band to 10.8% in the 60-90k band.
Methodology & source. Based on 9,975 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.