A buyer-focused explanation of major, minor and dangerous MOT defects and what each result means when reviewing a used car.
MOT defects are grouped by severity, and that classification helps a buyer understand how serious a recorded issue was at the time of the test. It is still important to read the actual defect wording rather than relying only on the category name.
A dangerous defect is the most serious level and means the vehicle should not be driven until the defect is repaired. If you see one in the history, check what work followed and whether there is evidence of a proper repair.
A major defect causes the MOT to fail. Major defects can range from braking or steering problems to lighting, emissions or structural concerns. The practical importance depends on the exact item and whether it recurs later.
Minor defects do not cause a failure but can still tell you about wear or maintenance. A long list of repeated minor items may indicate a car that has been maintained reactively rather than proactively.
Always compare historical defects with the current condition. A previous problem may have been fully resolved, while a clean recent MOT does not guarantee the vehicle has no mechanical issues today.
How to read an MOT record properly
A current MOT pass is useful, but the history behind it usually tells you more. Look at the pattern across several tests rather than treating the latest result as a complete verdict on the car.
What to check
Compare mileage readings from one test to the next.
Look for the same advisory appearing over several years.
Check whether failures are followed by repairs and a prompt pass.
Pay attention to corrosion, brakes, tyres, suspension and lighting defects that recur.
Why it matters
Repeated advisories can indicate maintenance that has been delayed rather than resolved. A single advisory is not necessarily serious, but the same issue returning year after year should influence the questions you ask the seller and what you inspect at the vehicle.
What the data cannot prove
An MOT confirms that the vehicle met the required test standard at the time of testing. It does not prove that the car is mechanically perfect today, and it does not check finance, theft, insurance write-off or salvage history.
