1985 Porsche 911 — MOT failures & pass rate
1,418 MOT tests on the 1985 Porsche 911 are in this dataset, and 85.3% of them passed. That is effectively the same as coupes & convertibles of a similar age (15.7% fail rate), so the MOT record here is unremarkable in either direction. Failures cluster in lighting & signalling, visibility and brakes.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 12.7% of tests against 4.9% for the next-worst category.
At component level the recurring items are headlamp aim, rear fog lamp and washers — headlamp aim alone was recorded 97 times.
Mileage matters less than usual here: the 1985 911 fails 17.3% of the time in the 0-30k band and 14.3% at 150k+, a spread of only 3.0 points.
Suspension is the most common advisory, noted on 10.7% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 15.9% in 2021 to 11.4% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 12.7% | 180 |
| 2 | Visibility | 4.9% | 70 |
| 3 | Brakes | 3.7% | 53 |
| 4 | Body, structure & corrosion | 2.2% | 31 |
| 5 | Emissions & environmental | 2.2% | 31 |
| 6 | Suspension | 1.6% | 23 |
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 | 97 |
| 2 | Rear fog lamp | 74 |
| 3 | Washers | 59 |
| 4 | Service brake performance | 58 |
| 5 | Position lamp | 50 |
| 6 | Stop lamp | 26 |
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 | 10.7% | 151 |
| 2 | Emissions & environmental | 9.4% | 133 |
| 3 | Brakes | 8.3% | 117 |
| 4 | Tyres | 6.1% | 86 |
| 5 | Body, structure & corrosion | 3.7% | 53 |
| 6 | Lighting & signalling | 3.3% | 47 |
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 | 110 | 17.3% |
| 30-60k | 100 | 12.0% |
| 60-90k | 316 | 14.6% |
| 90-120k | 473 | 14.6% |
| 120-150k | 292 | 15.1% |
| 150k+ | 126 | 14.3% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 283 | 15.9% |
| 2022 | 303 | 15.2% |
| 2023 | 285 | 14.7% |
| 2024 | 301 | 15.6% |
| 2025 | 246 | 11.4% |
What to check before buying a 1985 911
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 12.7% of tests. Start there.
- Lighting & signalling (12.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (4.9% 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 (3.7% 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 1985 Porsche 911s pass their MOT?
85.3% of the 1,418 1985 Porsche 911 MOT tests in this dataset passed — a 14.7% fail rate.
What is the most common MOT failure on a 1985 Porsche 911?
Lighting & signalling, recorded in 12.7% of tests, followed by visibility (4.9%).
Does the 1985 911 get worse with mileage?
Its MOT fail rate rises from 17.3% in the 0-30k band to 14.3% in the 150k+ band.
Methodology & source. Based on 1,418 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.