1997 Porsche 911 — MOT failures & pass rate
3,889 MOT tests on the 1997 Porsche 911 are in this dataset, and 90.2% of them passed. Against coupes & convertibles of a similar age (20.9% fail rate), the 1997 911 comes out 11.1pp better. Failures cluster in lighting & signalling, suspension and emissions & environmental.
What the MOT record shows
Lighting & signalling dominates the failure mix at 7.7% of all tests — 5.5 points clear of suspension, so it is the first thing to check.
At component level the recurring items are headlamp aim, position lamp and catalyst emissions — headlamp aim alone was recorded 107 times.
Mileage is the strongest signal on the record: 5.9% of 0-30k cars fail, rising to 13.9% once past 150k — 2.4× the risk.
Advisories point at the next bill rather than this one: emissions & environmental was flagged on 10.2% of tests without failing them.
The trend is improving — the fail rate fell from 11.3% in 2021 to 8.2% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 7.7% | 301 |
| 2 | Suspension | 2.2% | 86 |
| 3 | Emissions & environmental | 2.0% | 77 |
| 4 | Brakes | 1.5% | 60 |
| 5 | Visibility | 1.4% | 55 |
| 6 | Tyres | 0.9% | 36 |
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 | 107 |
| 2 | Position lamp | 80 |
| 3 | Catalyst emissions | 71 |
| 4 | Stop lamp | 68 |
| 5 | Headlamp | 64 |
| 6 | Rear fog lamp | 59 |
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 | 10.2% | 397 |
| 2 | Brakes | 9.8% | 379 |
| 3 | Tyres | 9.0% | 352 |
| 4 | Suspension | 7.6% | 296 |
| 5 | Lighting & signalling | 3.2% | 124 |
| 6 | Visibility | 2.2% | 85 |
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 | 273 | 5.9% |
| 30-60k | 931 | 6.7% |
| 60-90k | 1,477 | 9.6% |
| 90-120k | 807 | 13.6% |
| 120-150k | 297 | 12.1% |
| 150k+ | 101 | 13.9% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 828 | 11.3% |
| 2022 | 794 | 9.3% |
| 2023 | 783 | 10.1% |
| 2024 | 748 | 9.8% |
| 2025 | 736 | 8.2% |
What to check before buying a 1997 911
On a 1997 911, lighting & signalling is what the MOT record says goes wrong most — it appeared in 7.7% of tests. Check these areas before you commit.
- Lighting & signalling (7.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (2.2% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
- Emissions & environmental (2.0% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
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 1997 Porsche 911s pass their MOT?
90.2% of the 3,889 1997 Porsche 911 MOT tests in this dataset passed — a 9.8% fail rate.
What is the most common MOT failure on a 1997 Porsche 911?
Lighting & signalling, recorded in 7.7% of tests, followed by suspension (2.2%).
Does the 1997 911 get worse with mileage?
Its MOT fail rate rises from 5.9% in the 0-30k band to 13.9% in the 150k+ band.
Methodology & source. Based on 3,889 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.