1990 Porsche 911 — MOT failures & pass rate
The 1990 Porsche 911 passed 89.4% of its 3,667 recorded MOT tests. That is 7.5 percentage points better than coupes & convertibles of a similar age, which fail at 18.1%. Failures cluster in lighting & signalling, visibility and suspension.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 8.1% of tests against 2.4% for the next-worst category.
At component level the recurring items are headlamp aim, rear fog lamp and position lamp — headlamp aim alone was recorded 196 times.
Mileage matters less than usual here: the 1990 911 fails 9.4% of the time in the 0-30k band and 8.8% at 150k+, a spread of only 0.5 points.
Emissions & environmental is the most common advisory, noted on 14.4% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 12.5% in 2021 to 9.6% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 8.1% | 297 |
| 2 | Visibility | 2.4% | 87 |
| 3 | Suspension | 2.1% | 79 |
| 4 | Emissions & environmental | 1.8% | 66 |
| 5 | Brakes | 1.5% | 54 |
| 6 | Body, structure & corrosion | 1.4% | 50 |
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 | 196 |
| 2 | Rear fog lamp | 84 |
| 3 | Position lamp | 69 |
| 4 | Washers | 64 |
| 5 | Linkage ball joint dust cover | 56 |
| 6 | Stop lamp | 46 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Emissions & environmental | 14.4% | 530 |
| 2 | Suspension | 7.0% | 255 |
| 3 | Brakes | 6.7% | 246 |
| 4 | Tyres | 6.6% | 242 |
| 5 | Lighting & signalling | 2.4% | 87 |
| 6 | Other defects | 2.1% | 79 |
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 | 384 | 9.4% |
| 30-60k | 326 | 8.3% |
| 60-90k | 703 | 11.2% |
| 90-120k | 1,155 | 11.3% |
| 120-150k | 742 | 11.7% |
| 150k+ | 351 | 8.8% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 696 | 12.5% |
| 2022 | 788 | 11.3% |
| 2023 | 760 | 10.9% |
| 2024 | 705 | 8.8% |
| 2025 | 718 | 9.6% |
What to check before buying a 1990 911
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 8.1% of tests. Start there.
- Lighting & signalling (8.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (2.4% of tests): Wipers, washers, mirrors and screen damage — usually inexpensive, but check for chips in the driver's line of sight. Typical repair: £15–£150.
- Suspension (2.1% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
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 1990 Porsche 911s pass their MOT?
89.4% of the 3,667 1990 Porsche 911 MOT tests in this dataset passed — a 10.6% fail rate.
What is the most common MOT failure on a 1990 Porsche 911?
Lighting & signalling, recorded in 8.1% of tests, followed by visibility (2.4%).
Does the 1990 911 get worse with mileage?
Its MOT fail rate rises from 9.4% in the 0-30k band to 8.8% in the 150k+ band.
Methodology & source. Based on 3,667 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.