2021 Porsche Cayman — MOT failures & pass rate
Across 933 MOT tests, the 2021 Porsche Cayman recorded a 96.9% pass rate. Against coupes & convertibles of a similar age (7.9% fail rate), the 2021 Cayman comes out 4.8pp better. Failures cluster in tyres, lighting & signalling and other defects.
What the MOT record shows
No single area dominates — tyres (2.1%) and lighting & signalling (0.8%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are tread depth, headlamp aim and registration plates — tread depth alone was recorded 12 times.
Tyres is the most common advisory, noted on 11.9% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 2.1% | 20 |
| 2 | Lighting & signalling | 0.8% | 7 |
| 3 | Other defects | 0.3% | 3 |
| 4 | Visibility | 0.3% | 3 |
| 5 | Brakes | 0.2% | 2 |
| 6 | Emissions & environmental | 0.1% | 1 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Tread depth | 12 |
| 2 | Headlamp aim | 9 |
| 3 | Registration plates | 6 |
| 4 | Washers | 2 |
| 5 | Service brake imbalance | 2 |
| 6 | SRS malfunction indicator lamp | 1 |
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 | 11.9% | 111 |
| 2 | Other defects | 3.1% | 29 |
| 3 | Visibility | 1.8% | 17 |
| 4 | Brakes | 1.5% | 14 |
| 5 | Emissions & environmental | 0.5% | 5 |
| 6 | Road wheels | 0.4% | 4 |
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 | 836 | 2.5% |
| 30-60k | 94 | 8.5% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2024 | 456 | 3.5% |
| 2025 | 452 | 2.9% |
What to check before buying a 2021 Cayman
The failure pattern for this year is specific enough to inspect against: tyres accounted for 2.1% of tests. Start there.
- Tyres (2.1% 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 (0.8% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Other defects (0.3% 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 2021 Porsche Caymans pass their MOT?
96.9% of the 933 2021 Porsche Cayman MOT tests in this dataset passed — a 3.1% fail rate.
What is the most common MOT failure on a 2021 Porsche Cayman?
Tyres, recorded in 2.1% of tests, followed by lighting & signalling (0.8%).
Does the 2021 Cayman get worse with mileage?
Its MOT fail rate rises from 2.5% in the 0-30k band to 8.5% in the 30-60k band.
Methodology & source. Based on 933 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.