Every year the Driver and Vehicle Standards Agency (DVSA) publishes anonymised MOT testing data for Great Britain. The exact percentages shift slightly year to year, but the same groups of defects dominate: lamps and electrical, suspension, tyres and brakes. Understanding those patterns helps you prepare your own car — and spot risk in a used car’s history.
Figures below are described in plain language from DVSA open MOT statistical data sets on GOV.UK. Always check the latest tables if you need a citation for a precise percentage, because annual releases update.
Why “common failures” matter
- Owners: a 20-minute checklist prevents many lamp and tyre fails.
- Buyers: repeated fails or advisories in the same category across years often mean neglected maintenance.
- Budgeting: brakes and suspension repairs are predictable cost centres on older cars.
The usual top categories
- Lamps, reflectors and electrical — blown bulbs, aim, damaged lenses, wiring faults.
- Suspension — worn joints, springs, shock absorbers, corrosion on related structures.
- Tyres — tread below limit, damage, cord exposed; tyres also account for a large share of dangerous defects when they fail badly.
- Brakes — pads, discs, lines, imbalance, ABS-related issues.
Visibility items (wipers, washers, glass) and body/structure corrosion also appear often on older vehicles.
Dangerous vs major vs minor
Since 2018, defects are graded. Dangerous and major defects fail the test. Minor defects are recorded on a pass but should be fixed soon. Advisories are “watch this” items. Full definitions: see DVSA guidance and our advisories explained page.
How to use this when buying
On a free MOT history check, scan for:
- The same brake or tyre wording year after year.
- A fail for corrosion followed by a quick pass with more corrosion advisories — ask what was welded and whether it was structural.
- Mileage that stalls or drops between tests — see spotting clocked mileage.
Model-specific “worst cars” lists in the press are often age-biased. Prefer age-adjusted thinking: a ten-year-old city runabout will show more advisories than a three-year-old car even when both are average for their age.
Prevention checklist (short)
Lights, tyre tread and pressure, wipers/washers, horn, seatbelts, warning lights, number plates — detail in our prepare for MOT checklist.
Official sources
Used Car Checker is independent of DVSA. We help you read the same public history with buyer-focused tools; we do not replace official advice.
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