Ford Sierra MOT pass rate & common failures
Across 41 model years and 13,084 tests, the Ford Sierra passes its MOT 88.3% of the time. That is 1.9 percentage points better than large family cars of a similar age, which fail at 13.6%. Its most common failure areas are lighting & signalling, suspension and emissions & environmental.
Best and worst Sierra years
Ranked across Sierra years with at least 1,000 tests. Older cars fail more simply because they are older — compare years close together in age before drawing conclusions.
What the MOT record shows
Build year matters more than the headline suggests: 1986 cars pass 92.7% of the time while 1992 cars manage 84.8%, a 7.9-point spread.
No single area dominates — lighting & signalling (6.0%) and suspension (4.3%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are component mounting prescribed areas, headlamp aim and non catalyst emissions — component mounting prescribed areas alone was recorded 477 times.
A 120-150k example is materially riskier than a 0-30k one: 7.9% versus 12.0%.
Advisories point at the next bill rather than this one: suspension was flagged on 12.1% of tests without failing them.
The trend is improving — the fail rate fell from 13.4% in 2021 to 9.7% in 2025, as the worst-kept examples leave the fleet.
How it compares
By model year
Every Sierra model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 1983 | 534 | 87.6% | 12.4% | Lighting & signalling |
| 1984 | 647 | 89.8% | 10.2% | Lighting & signalling |
| 1985 | 222 | 86.9% | 13.1% | Lighting & signalling |
| 1986 | 1,161 | 92.7% | 7.3% | Lighting & signalling |
| 1987 | 1,913 | 91.6% | 8.4% | Lighting & signalling |
| 1988 | 1,107 | 87.7% | 12.3% | Lighting & signalling |
| 1989 | 1,732 | 87.2% | 12.8% | Lighting & signalling |
| 1990 | 1,810 | 87.9% | 12.1% | Lighting & signalling |
| 1991 | 1,599 | 87.7% | 12.3% | Lighting & signalling |
| 1992 | 1,718 | 84.8% | 15.3% | Lighting & signalling |
| 1993 | 546 | 85.2% | 14.8% | Lighting & signalling |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 6.0% | 789 |
| 2 | Suspension | 4.3% | 561 |
| 3 | Emissions & environmental | 3.7% | 487 |
| 4 | Brakes | 3.6% | 470 |
| 5 | Body, structure & corrosion | 3.5% | 451 |
| 6 | Visibility | 2.3% | 306 |
| 7 | Steering | 1.5% | 197 |
| 8 | Seat belts & restraints | 1.1% | 151 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Component mounting prescribed areas | 477 |
| 2 | Headlamp aim | 326 |
| 3 | Non catalyst emissions | 319 |
| 4 | Headlamp | 226 |
| 5 | Prescribed areas | 195 |
| 6 | Service brake performance | 192 |
| 7 | Integral vehicle structure condition | 187 |
| 8 | Washers | 183 |
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 | 12.1% | 1,589 |
| 2 | Brakes | 12.0% | 1,566 |
| 3 | Emissions & environmental | 9.8% | 1,289 |
| 4 | Body, structure & corrosion | 8.7% | 1,144 |
| 5 | Tyres | 7.1% | 926 |
| 6 | Other defects | 5.7% | 744 |
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 | 3,874 | 12.0% |
| 30-60k | 3,551 | 12.3% |
| 60-90k | 3,922 | 11.6% |
| 90-120k | 1,618 | 10.0% |
| 120-150k | 63 | 7.9% |
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 12,855 | 11.6% |
| Diesel | 229 | 16.2% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 2,876 | 13.4% |
| 2022 | 2,779 | 12.8% |
| 2023 | 2,660 | 11.4% |
| 2024 | 2,436 | 10.7% |
| 2025 | 2,333 | 9.7% |
What to check before buying a Ford Sierra
- Lighting & signalling (6.0% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (4.3% 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 (3.7% 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
What is the MOT pass rate for the Ford Sierra?
88.3% of the 13,084 Ford Sierra MOT tests in this dataset passed, an 11.7% fail rate, across model years 1981–2021.
What does the Ford Sierra most often fail its MOT on?
Lighting & signalling, recorded in 6.0% of tests, then suspension (4.3%).
Which Sierra years are best and worst for MOT results?
1986 has the best pass rate at 92.7% and 1992 the weakest at 84.8%, from 1,161 and 1,718 tests respectively.
How much does mileage affect Sierra MOT results?
Fail rates run at 12.0% for cars in the 0-30k band and 7.9% for 120-150k, a 4.1-point difference.
Methodology & source. Based on 13,084 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.