1986 Porsche 911 — MOT failures & pass rate
Across 1,810 MOT tests, the 1986 Porsche 911 recorded an 86.7% pass rate. Against coupes & convertibles of a similar age (16.1% fail rate), the 1986 911 comes out 2.8pp better. Failures cluster in lighting & signalling, visibility and brakes.
What the MOT record shows
Lighting & signalling dominates the failure mix at 8.8% of all tests — 4.1 points clear of visibility, so it is the first thing to check.
At component level the recurring items are headlamp aim, washers and rear fog lamp — headlamp aim alone was recorded 92 times.
A 150k+ example is materially riskier than a 0-30k one: 16.1% versus 9.4%.
Advisories point at the next bill rather than this one: suspension was flagged on 9.9% of tests without failing them.
The trend is improving — the fail rate fell from 14.1% in 2021 to 11.3% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 8.8% | 160 |
| 2 | Visibility | 4.8% | 86 |
| 3 | Brakes | 2.6% | 48 |
| 4 | Emissions & environmental | 2.1% | 39 |
| 5 | Body, structure & corrosion | 1.6% | 29 |
| 6 | Suspension | 1.3% | 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 | 92 |
| 2 | Washers | 80 |
| 3 | Rear fog lamp | 68 |
| 4 | Service brake performance | 40 |
| 5 | Position lamp | 33 |
| 6 | Non catalyst emissions | 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 | 9.9% | 180 |
| 2 | Emissions & environmental | 8.0% | 144 |
| 3 | Brakes | 7.1% | 129 |
| 4 | Tyres | 5.7% | 103 |
| 5 | Lighting & signalling | 3.7% | 67 |
| 6 | Body, structure & corrosion | 2.8% | 51 |
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 | 159 | 9.4% |
| 30-60k | 264 | 11.0% |
| 60-90k | 370 | 13.5% |
| 90-120k | 487 | 13.4% |
| 120-150k | 342 | 14.9% |
| 150k+ | 186 | 16.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 347 | 14.1% |
| 2022 | 403 | 12.7% |
| 2023 | 350 | 13.7% |
| 2024 | 356 | 14.6% |
| 2025 | 354 | 11.3% |
What to check before buying a 1986 911
On a 1986 911, lighting & signalling is what the MOT record says goes wrong most — it appeared in 8.8% of tests. Check these areas before you commit.
- Lighting & signalling (8.8% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (4.8% 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 (2.6% 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 1986 Porsche 911s pass their MOT?
86.7% of the 1,810 1986 Porsche 911 MOT tests in this dataset passed — a 13.3% fail rate.
What is the most common MOT failure on a 1986 Porsche 911?
Lighting & signalling, recorded in 8.8% of tests, followed by visibility (4.8%).
Does the 1986 911 get worse with mileage?
Its MOT fail rate rises from 9.4% in the 0-30k band to 16.1% in the 150k+ band.
Methodology & source. Based on 1,810 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.