1989 Porsche 928 S — MOT failures & pass rate
The 1989 Porsche 928 S passed 81.8% of its 440 recorded MOT tests. That is 3.2 percentage points better than all cars of a similar age, which fail at 21.3%. Failures cluster in lighting & signalling, brakes and visibility.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 11.6% of tests against 4.5% for the next-worst category.
At component level the recurring items are headlamp aim, washers and non catalyst emissions — headlamp aim alone was recorded 23 times.
Mileage matters less than usual here: the 1989 928 S fails 18.4% of the time in the 30-60k band and 21.1% at 150k+, a spread of only 2.7 points.
Suspension is the most common advisory, noted on 17.7% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 22.6% in 2021 to 17.8% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 11.6% | 51 |
| 2 | Brakes | 4.5% | 20 |
| 3 | Visibility | 4.3% | 19 |
| 4 | Body, structure & corrosion | 4.1% | 18 |
| 5 | Emissions & environmental | 3.4% | 15 |
| 6 | Steering | 2.7% | 12 |
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 | 23 |
| 2 | Washers | 14 |
| 3 | Non catalyst emissions | 12 |
| 4 | Joints | 10 |
| 5 | Position lamp | 10 |
| 6 | Stop lamp | 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 | 17.7% | 78 |
| 2 | Other defects | 16.8% | 74 |
| 3 | Emissions & environmental | 14.8% | 65 |
| 4 | Brakes | 13.2% | 58 |
| 5 | Tyres | 10.9% | 48 |
| 6 | Body, structure & corrosion | 8.9% | 39 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 30-60k | 38 | 18.4% |
| 60-90k | 57 | 17.5% |
| 90-120k | 147 | 16.3% |
| 120-150k | 119 | 19.3% |
| 150k+ | 71 | 21.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 106 | 22.6% |
| 2022 | 98 | 20.4% |
| 2023 | 81 | 13.6% |
| 2024 | 82 | 14.6% |
| 2025 | 73 | 17.8% |
What to check before buying a 1989 928 S
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 11.6% of tests. Start there.
- Lighting & signalling (11.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (4.5% 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.
- Visibility (4.3% 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.
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 1989 Porsche 928 Ss pass their MOT?
81.8% of the 440 1989 Porsche 928 S MOT tests in this dataset passed — a 18.2% fail rate.
What is the most common MOT failure on a 1989 Porsche 928 S?
Lighting & signalling, recorded in 11.6% of tests, followed by brakes (4.5%).
Does the 1989 928 S get worse with mileage?
Its MOT fail rate rises from 18.4% in the 30-60k band to 21.1% in the 150k+ band.
Methodology & source. Based on 440 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.