1981 Porsche 911 — MOT failures & pass rate
The 1981 Porsche 911 passed 86.0% of its 400 recorded MOT tests. Against coupes & convertibles of a similar age (13.0% fail rate), the 1981 911 comes out 1.0pp worse. Failures cluster in lighting & signalling, visibility and brakes.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 10.8% of tests against 4.0% for the next-worst category.
At component level the recurring items are headlamp aim, rear fog lamp and washers — headlamp aim alone was recorded 24 times.
Mileage matters less than usual here: the 1981 911 fails 12.0% of the time in the 0-30k band and 15.8% at 150k+, a spread of only 3.8 points.
Suspension is the most common advisory, noted on 9.5% of tests — work that passed today but is likely due soon.
The trend is worsening — 11.5% of tests failed in 2021 against 14.3% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 10.8% | 43 |
| 2 | Visibility | 4.0% | 16 |
| 3 | Brakes | 2.8% | 11 |
| 4 | Emissions & environmental | 2.3% | 9 |
| 5 | Body, structure & corrosion | 1.8% | 7 |
| 6 | Steering | 1.8% | 7 |
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 | 24 |
| 2 | Rear fog lamp | 20 |
| 3 | Washers | 15 |
| 4 | Service brake performance | 15 |
| 5 | Position lamp | 14 |
| 6 | Headlamp | 9 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Suspension | 9.5% | 38 |
| 2 | Emissions & environmental | 7.0% | 28 |
| 3 | Tyres | 4.5% | 18 |
| 4 | Brakes | 4.0% | 16 |
| 5 | Lighting & signalling | 2.8% | 11 |
| 6 | Seat belts & restraints | 2.3% | 9 |
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 | 50 | 12.0% |
| 30-60k | 39 | 12.8% |
| 60-90k | 91 | 8.8% |
| 90-120k | 92 | 19.6% |
| 120-150k | 70 | 14.3% |
| 150k+ | 57 | 15.8% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 130 | 11.5% |
| 2022 | 98 | 18.4% |
| 2023 | 60 | 16.7% |
| 2024 | 56 | 8.9% |
| 2025 | 56 | 14.3% |
What to check before buying a 1981 911
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 10.8% of tests. Start there.
- Lighting & signalling (10.8% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (4.0% 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.
- Brakes (2.8% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
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 1981 Porsche 911s pass their MOT?
86.0% of the 400 1981 Porsche 911 MOT tests in this dataset passed — a 14.0% fail rate.
What is the most common MOT failure on a 1981 Porsche 911?
Lighting & signalling, recorded in 10.8% of tests, followed by visibility (4.0%).
Does the 1981 911 get worse with mileage?
Its MOT fail rate rises from 12.0% in the 0-30k band to 15.8% in the 150k+ band.
Methodology & source. Based on 400 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.