Mercedes-Benz 420: lighting & signalling MOT failures
Lighting & signalling was a recorded failure area in 9.0% of Mercedes-Benz 420 MOT tests in this dataset. It is most prominent on 1987 cars.
Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair cost: £10–£150 (rough UK ballpark, not a quote).
Lighting & signalling failures by year
| Model year | Tests | Fail rate |
|---|---|---|
| 1987 | 868 | 8.8% |
Methodology & source. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-01. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.