2020 Porsche 911 Carrera 4 — MOT failures & pass rate
Across 558 MOT tests, the 2020 Porsche 911 Carrera 4 recorded a 95.3% pass rate. Against all cars of a similar age (9.3% fail rate), the 2020 911 Carrera 4 comes out 4.7pp better. Failures cluster in tyres, lighting & signalling and other defects.
What the MOT record shows
Tyres dominates the failure mix at 4.3% of all tests — 3.8 points clear of lighting & signalling, so it is the first thing to check.
At component level the recurring items are tread depth, registration plates and headlamp aim — tread depth alone was recorded 17 times.
Advisories point at the next bill rather than this one: tyres was flagged on 13.1% of tests without failing them.
The trend is improving — the fail rate fell from 5.0% in 2023 to 3.4% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.3% | 24 |
| 2 | Lighting & signalling | 0.5% | 3 |
| 3 | Other defects | 0.5% | 3 |
| 4 | Brakes | 0.5% | 3 |
| 5 | Visibility | 0.2% | 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 | 17 |
| 2 | Registration plates | 5 |
| 3 | Headlamp aim | 4 |
| 4 | Brake pads | 2 |
| 5 | Brake performance not tested | 1 |
| 6 | Service brake performance | 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 | 13.1% | 73 |
| 2 | Other defects | 4.5% | 25 |
| 3 | Visibility | 1.4% | 8 |
| 4 | Brakes | 0.9% | 5 |
| 5 | Road wheels | 0.5% | 3 |
| 6 | Emissions & environmental | 0.2% | 1 |
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 | 483 | 3.9% |
| 30-60k | 72 | 9.7% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2023 | 181 | 5.0% |
| 2024 | 192 | 5.2% |
| 2025 | 176 | 3.4% |
What to check before buying a 2020 911 Carrera 4
On a 2020 911 Carrera 4, tyres is what the MOT record says goes wrong most — it appeared in 4.3% of tests. Check these areas before you commit.
- Tyres (4.3% 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 (0.5% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Other defects (0.5% 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 2020 Porsche 911 Carrera 4s pass their MOT?
95.3% of the 558 2020 Porsche 911 Carrera 4 MOT tests in this dataset passed — a 4.7% fail rate.
What is the most common MOT failure on a 2020 Porsche 911 Carrera 4?
Tyres, recorded in 4.3% of tests, followed by lighting & signalling (0.5%).
Does the 2020 911 Carrera 4 get worse with mileage?
Its MOT fail rate rises from 3.9% in the 0-30k band to 9.7% in the 30-60k band.
Methodology & source. Based on 558 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.