1986 Porsche 928 S — MOT failures & pass rate
The 1986 Porsche 928 S passed 81.3% of its 396 recorded MOT tests. All cars of a similar age fail 20.4% of the time, so this is 1.7pp better than the group it competes with. Failures cluster in lighting & signalling, visibility and body, structure & corrosion.
What the MOT record shows
Lighting & signalling dominates the failure mix at 12.6% of all tests — 3.8 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 36 times.
Mileage matters less than usual here: the 1986 928 S fails 16.5% of the time in the 60-90k band and 14.6% at 150k+, a spread of only 1.9 points.
Advisories point at the next bill rather than this one: emissions & environmental was flagged on 25.5% of tests without failing them.
The trend is improving — the fail rate fell from 18.3% in 2021 to 15.0% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 12.6% | 50 |
| 2 | Visibility | 8.8% | 35 |
| 3 | Body, structure & corrosion | 4.5% | 18 |
| 4 | Emissions & environmental | 3.3% | 13 |
| 5 | Brakes | 3.3% | 13 |
| 6 | Steering | 3.3% | 13 |
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 | 36 |
| 2 | Washers | 35 |
| 3 | Rear fog lamp | 17 |
| 4 | Joints | 12 |
| 5 | Steering rack | 11 |
| 6 | Wipers | 10 |
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 | 25.5% | 101 |
| 2 | Suspension | 21.7% | 86 |
| 3 | Brakes | 10.6% | 42 |
| 4 | Other defects | 9.3% | 37 |
| 5 | Tyres | 8.8% | 35 |
| 6 | Body, structure & corrosion | 7.8% | 31 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 60-90k | 91 | 16.5% |
| 90-120k | 108 | 23.2% |
| 120-150k | 101 | 14.8% |
| 150k+ | 48 | 14.6% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 82 | 18.3% |
| 2022 | 78 | 20.5% |
| 2023 | 85 | 21.2% |
| 2024 | 71 | 18.3% |
| 2025 | 80 | 15.0% |
What to check before buying a 1986 928 S
On a 1986 928 S, lighting & signalling is what the MOT record says goes wrong most — it appeared in 12.6% of tests. Check these areas before you commit.
- Lighting & signalling (12.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (8.8% 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.
- Body, structure & corrosion (4.5% of tests): The one to take seriously on older cars — corrosion to structural areas can be costly and is an MOT failure. Typical repair: £200–£1,500+.
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 928 Ss pass their MOT?
81.3% of the 396 1986 Porsche 928 S MOT tests in this dataset passed — a 18.7% fail rate.
What is the most common MOT failure on a 1986 Porsche 928 S?
Lighting & signalling, recorded in 12.6% of tests, followed by visibility (8.8%).
Does the 1986 928 S get worse with mileage?
Its MOT fail rate rises from 16.5% in the 60-90k band to 14.6% in the 150k+ band.
Methodology & source. Based on 396 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.