Porsche 911 Carrera 4 MOT pass rate & common failures
Across 35 model years and 1,376 tests, the Porsche 911 Carrera 4 passes its MOT 92.1% of the time. That is 6.2 percentage points better than all cars of a similar age, which fail at 14.2%. Its most common failure areas are tyres, lighting & signalling and emissions & environmental.
What the MOT record shows
No single area dominates — tyres (3.8%) and lighting & signalling (3.0%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, tread depth and catalyst emissions — headlamp aim alone was recorded 32 times.
A 120-150k example is materially riskier than a 0-30k one: 23.3% versus 4.5%.
Advisories point at the next bill rather than this one: tyres was flagged on 13.8% of tests without failing them.
The trend is improving — the fail rate fell from 20.0% in 2021 to 6.1% in 2025, as the worst-kept examples leave the fleet.
How it compares
By model year
Every 911 Carrera 4 model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 2001 | 52 | 82.7% | 17.3% | Body, structure & corrosion |
| 2002 | 140 | 80.0% | 20.0% | Lighting & signalling |
| 2003 | 94 | 88.3% | 11.7% | Lighting & signalling |
| 2019 | 256 | 94.5% | 5.5% | Tyres |
| 2020 | 558 | 95.3% | 4.7% | Tyres |
| 2021 | 130 | 94.6% | 5.4% | Tyres |
| 2022 | 40 | 95.0% | 5.0% | Tyres |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 3.8% | 52 |
| 2 | Lighting & signalling | 3.0% | 42 |
| 3 | Emissions & environmental | 1.5% | 20 |
| 4 | Brakes | 1.2% | 17 |
| 5 | Body, structure & corrosion | 1.0% | 14 |
| 6 | Suspension | 0.9% | 12 |
| 7 | Visibility | 0.7% | 9 |
| 8 | Other defects | 0.6% | 8 |
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 | 32 |
| 2 | Tread depth | 28 |
| 3 | Catalyst emissions | 22 |
| 4 | Registration plates | 13 |
| 5 | Linkage ball joint dust cover | 11 |
| 6 | Rigid brake pipes | 10 |
| 7 | Headlamp | 9 |
| 8 | Exhaust system | 8 |
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 | 13.8% | 190 |
| 2 | Brakes | 6.3% | 86 |
| 3 | Other defects | 3.8% | 52 |
| 4 | Suspension | 3.4% | 47 |
| 5 | Emissions & environmental | 2.4% | 33 |
| 6 | Visibility | 2.0% | 28 |
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 | 899 | 4.5% |
| 30-60k | 187 | 9.1% |
| 60-90k | 177 | 19.8% |
| 90-120k | 78 | 10.3% |
| 120-150k | 30 | 23.3% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 80 | 20.0% |
| 2022 | 143 | 11.9% |
| 2023 | 330 | 6.7% |
| 2024 | 395 | 7.1% |
| 2025 | 428 | 6.1% |
What to check before buying a Porsche 911 Carrera 4
- Tyres (3.8% 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 (3.0% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Emissions & environmental (1.5% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
What is the MOT pass rate for the Porsche 911 Carrera 4?
92.1% of the 1,376 Porsche 911 Carrera 4 MOT tests in this dataset passed, a 7.9% fail rate, across model years 1989–2023.
What does the Porsche 911 Carrera 4 most often fail its MOT on?
Tyres, recorded in 3.8% of tests, then lighting & signalling (3.0%).
How much does mileage affect 911 Carrera 4 MOT results?
Fail rates run at 4.5% for cars in the 0-30k band and 23.3% for 120-150k, a 18.9-point difference.
Methodology & source. Based on 1,376 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.