1986 Ford Sierra — MOT failures & pass rate
Across 1,161 MOT tests, the 1986 Ford Sierra recorded a 92.7% pass rate. Against large family cars of a similar age (10.5% fail rate), the 1986 Sierra comes out 3.2pp better. Failures cluster in lighting & signalling, brakes and emissions & environmental.
What the MOT record shows
No single area dominates — lighting & signalling (4.3%) and brakes (2.4%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, non catalyst emissions and washers — headlamp aim alone was recorded 30 times.
Mileage matters less than usual here: the 1986 Sierra fails 7.0% of the time in the 0-30k band and 5.7% at 90-120k, a spread of only 1.4 points.
The trend is improving — the fail rate fell from 10.3% in 2021 to 4.9% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 4.3% | 50 |
| 2 | Brakes | 2.4% | 28 |
| 3 | Emissions & environmental | 2.2% | 26 |
| 4 | Suspension | 2.1% | 24 |
| 5 | Visibility | 1.8% | 21 |
| 6 | Steering | 1.2% | 14 |
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 | 30 |
| 2 | Non catalyst emissions | 20 |
| 3 | Washers | 15 |
| 4 | Steering rack | 13 |
| 5 | Horn | 13 |
| 6 | Service brake performance | 12 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 6.3% | 73 |
| 2 | Suspension | 5.9% | 69 |
| 3 | Emissions & environmental | 4.9% | 57 |
| 4 | Body, structure & corrosion | 4.5% | 52 |
| 5 | Steering | 3.1% | 36 |
| 6 | Tyres | 3.1% | 36 |
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 | 312 | 7.0% |
| 30-60k | 282 | 8.2% |
| 60-90k | 434 | 7.4% |
| 90-120k | 123 | 5.7% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 233 | 10.3% |
| 2022 | 238 | 8.8% |
| 2023 | 233 | 7.7% |
| 2024 | 231 | 4.8% |
| 2025 | 226 | 4.9% |
What to check before buying a 1986 Sierra
On a 1986 Sierra, lighting & signalling is what the MOT record says goes wrong most — it appeared in 4.3% of tests. Check these areas before you commit.
- Lighting & signalling (4.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (2.4% 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.
- Emissions & environmental (2.2% 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 1986 Ford Sierras pass their MOT?
92.7% of the 1,161 1986 Ford Sierra MOT tests in this dataset passed — a 7.3% fail rate.
What is the most common MOT failure on a 1986 Ford Sierra?
Lighting & signalling, recorded in 4.3% of tests, followed by brakes (2.4%).
Does the 1986 Sierra get worse with mileage?
Its MOT fail rate rises from 7.0% in the 0-30k band to 5.7% in the 90-120k band.
Methodology & source. Based on 1,161 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.