Fiat Dethleffs MOT pass rate & common failures
1,207 MOT tests on the Fiat Dethleffs (1992–2022) give it a 92.9% pass rate. That is 6.1 percentage points better than all cars of a similar age, which fail at 13.2%. Its most common failure areas are lighting & signalling, visibility and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (4.1%) and visibility (3.1%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are wipers, headlamp aim and outline marker lamp — wipers alone was recorded 38 times.
Mileage is the strongest signal on the record: 6.4% of 0-30k cars fail, rising to 21.9% once past 60-90k — 3.4× the risk.
The trend is improving — the fail rate fell from 10.1% in 2021 to 7.2% in 2025, as the worst-kept examples leave the fleet.
How it compares
By model year
Every Dethleffs model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 2013 | 61 | 90.2% | 9.8% | Brakes |
| 2016 | 30 | 86.7% | 13.3% | Brakes |
| 2017 | 184 | 94.0% | 6.0% | Visibility |
| 2018 | 394 | 95.7% | 4.3% | Lighting & signalling |
| 2019 | 202 | 94.1% | 5.9% | Visibility |
| 2020 | 102 | 91.2% | 8.8% | Visibility |
| 2021 | 41 | 92.7% | 7.3% | Lighting & signalling |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 4.1% | 50 |
| 2 | Visibility | 3.1% | 37 |
| 3 | Brakes | 2.1% | 25 |
| 4 | Seat belts & restraints | 1.0% | 12 |
| 5 | Tyres | 0.7% | 8 |
| 6 | Emissions & environmental | 0.6% | 7 |
| 7 | Body, structure & corrosion | 0.5% | 6 |
| 8 | Suspension | 0.3% | 3 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Wipers | 38 |
| 2 | Headlamp aim | 19 |
| 3 | Outline marker lamp | 18 |
| 4 | Rbt (sp) | 11 |
| 5 | Washers | 11 |
| 6 | SRS malfunction indicator lamp | 10 |
| 7 | Service brake performance | 9 |
| 8 | Rear fog 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 | Tyres | 7.7% | 93 |
| 2 | Brakes | 3.9% | 47 |
| 3 | Lighting & signalling | 3.2% | 39 |
| 4 | Suspension | 2.0% | 24 |
| 5 | Visibility | 1.7% | 20 |
| 6 | Other defects | 1.2% | 15 |
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 | 1,006 | 6.4% |
| 30-60k | 156 | 7.0% |
| 60-90k | 32 | 21.9% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 158 | 10.1% |
| 2022 | 215 | 5.1% |
| 2023 | 246 | 4.9% |
| 2024 | 284 | 8.8% |
| 2025 | 304 | 7.2% |
What to check before buying a Fiat Dethleffs
- Lighting & signalling (4.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (3.1% 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.
- Brakes (2.1% 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.
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 Fiat Dethleffs?
92.9% of the 1,207 Fiat Dethleffs MOT tests in this dataset passed, a 7.1% fail rate, across model years 1992–2022.
What does the Fiat Dethleffs most often fail its MOT on?
Lighting & signalling, recorded in 4.1% of tests, then visibility (3.1%).
How much does mileage affect Dethleffs MOT results?
Fail rates run at 6.4% for cars in the 0-30k band and 21.9% for 60-90k, a 15.5-point difference.
Methodology & source. Based on 1,207 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.