MOT buyer insight · Updated 2026
MOT Advisory vs Failure
Four words on an MOT report — advisory, minor, major, dangerous — decide whether a car passed, whether it's legal to drive, and how much you should really be paying for it. Here's what each one actually means.
The four MOT defect categories
Since the DVSA's May 2018 reform, every UK MOT defect is logged under one of these four labels — not just a vague "advisory or fail."
Advisory
PASSInformal guidance from the tester about something worth monitoring. Doesn't affect the result.
e.g. A tyre nearing the legal tread limit, or a slight oil weep.
Minor defect
PASSA formally logged fault that doesn't affect safety or emissions enough to fail the car.
e.g. A slightly corroded number plate, or a washer bottle with low fluid.
Major defect
FAILA fault that affects safety, roadworthiness or the environment. Fails the test until repaired.
e.g. A brake pad worn below the legal minimum, or a misaligned headlamp.
Dangerous defect
FAILAn immediate, direct safety risk. Fails the test and the car cannot legally be driven until fixed.
e.g. A snapped coil spring, or a brake pipe close to failure.
Advisories: The Early Warning System Most Buyers Ignore
An advisory is the tester telling you something is worth watching, even though it didn't stop the car passing on the day. Sellers routinely wave these away as irrelevant precisely because they don't appear as a fail — but a report full of advisories is not a neutral document, it's a maintenance history written by a stranger with no reason to flatter the car.
- Brake or tyre advisories almost always mean genuine wear that's already progressing — expect to pay for that replacement soon, whatever the seller says about "plenty of life left."
- Electrical advisories (a warning light, an intermittent connector) are the ones to take most seriously, because they're often the cheapest thing to note and the most expensive thing to actually diagnose.
- Corrosion advisories near suspension mounts or sills rarely reverse themselves. An advisory this year is very often a major or dangerous defect two or three MOTs from now.
The pattern matters more than any single advisory. One isolated note on an otherwise clean multi-year history is normal wear. The same advisory reappearing on consecutive tests is a car whose owner chose not to fix it — see our full used car history red flags checklist for how this fits into the wider picture beyond just the MOT record.
Minor Defect vs Advisory — The Distinction That Trips Up Even Experienced Buyers
These two get treated as interchangeable, and they're close enough in practice that it rarely matters which one you're looking at — both let the car pass, and both are things a mechanic would want to know about before you buy. The real difference is procedural rather than practical: a minor defect is formally logged against a specific inspection item on the tester's checklist, while an advisory is closer to a free-text note the tester adds when something catches their eye that isn't tied to a strict pass/fail item.
What actually matters for you as a buyer isn't the label — it's the same question either way: what specifically was noted, and is it still true today? A "minor" tyre defect from eleven months ago is a different car to view than the same note from three days ago.
Major Defects, System by System
A major defect fails the test — no exceptions — but "major" covers a wide range of severity underneath that one label, from moderately serious to nearly dangerous. Knowing what's typical for each system helps you judge how worried to actually be:
- Brakes: pad or disc wear below the legal minimum, or uneven braking effort between wheels.
- Steering and suspension: excessive play in a joint, or a component showing significant wear without yet being an immediate failure risk.
- Tyres: tread depth below 1.6mm, or a cut or bulge in the sidewall.
- Lighting: a headlamp aimed incorrectly, or a brake light that doesn't function.
- Emissions: smoke or CO output beyond the limit for the vehicle's age and fuel type.
Every one of these is logged with a specific Reason for Rejection (RfR) code rather than just the system name, and the exact code tells you far more than the category label alone. We break down how to read those codes in MOT failure codes explained.
Dangerous Defects: The Only Category That Legally Grounds the Car
This is the one label on an MOT report with real legal weight attached. A dangerous defect doesn't just fail the test — it means the vehicle is not legally permitted on a public road at all until the fault is fixed, full stop. Typical examples include a severely corroded structural point, a brake pipe close to failing, a steering component with excessive play close to disconnection, or a tyre with cords visible through the tread.
Finding a past dangerous defect on a car's history isn't automatically a dealbreaker — plenty of cars have one, get properly repaired, and go on to pass every test since without issue. What matters is whether you can verify that happened. Ask for the repair invoice from a qualified garage and the MOT certificate from the retest that followed. If a seller can only offer one of the two, or neither, treat the defect as still open. Full detail on this category specifically is in what a "dangerous" advisory really means.
How This Looks Inside a Full MOT History Report
Knowing the four categories is only half the job — you also need to actually find them in a real report rather than skimming for the pass/fail headline. Each test lists every item checked, the result against it, and which of the four categories applied, going back as far as the vehicle's records extend. Reading that list properly, test by test, is what turns a database entry into an actual maintenance history you can trust. We walk through the process step by step in how to read an MOT history check: 9 key signals every buyer must know.
Turning Defect History Into a Negotiation
Use the category, not just the presence of a defect, to set your offer. A car with a clean run of passes and the occasional isolated advisory should be priced close to what the seller is asking. A car carrying multiple advisories on the same system, or a major defect resolved without clear proof, has real, quantifiable cost sitting in its near future — price accordingly, not on how the car looks in the driveway.
| Category | Result | Buyer action |
|---|---|---|
| Advisory | Pass | Ask when it first appeared, and whether it's been addressed since. |
| Minor defect | Pass | Check the component's current condition in person, not just on paper. |
| Major defect | Fail | Require a repair invoice and proof of a subsequent pass. |
| Dangerous defect | Fail | Only proceed with full repair records and a fresh pass certificate. |
Three questions cover most of what you need to ask a seller directly:
- When did this advisory or defect first appear on the record?
- Was the repair carried out by a professional garage, and do you have the invoice?
- Has the car been retested since, and did it pass cleanly?
Mistakes Even Careful Buyers Make
- Assuming "advisory" means "nothing to worry about." It means a professional flagged something — the question is whether it's since been fixed, not whether it exists.
- Assuming a clean pass means a mechanically sound car. A pass certificate only proves the car met the legal minimum on the day it was tested, not that it's in good overall condition.
- Judging a defect by its category alone, without checking if it recurred. A single major defect three years ago is a different risk profile to the same one repeating across three consecutive tests.
- Not checking the wider history alongside the MOT record. Defect categories tell you about mechanical condition — they say nothing about finance, theft or write-off status, which need a separate check covered in our full red flags checklist.
Frequently Asked Questions
Is an MOT advisory a reason to walk away from a car?
Not on its own — advisories are common even on well-maintained cars. But repeated advisories on the same component across multiple tests suggest neglected maintenance, and that's a fair reason to reduce your offer or walk away.
Can a car pass its MOT with a major defect?
No. A major defect always fails the test, with no exceptions. Only advisory and minor defects allow a car to pass — anything logged as major or dangerous means the car failed on the day it was tested.
What's the real difference between a minor defect and an advisory?
Both let the car pass, but a minor defect is a logged fault the tester has formally recorded as needing attention, while an advisory is closer to informal guidance. In practice, treat both the same way: as a maintenance item to ask the seller about.
How many advisories on one MOT should worry a buyer?
There's no fixed number — context matters more than count. Three advisories on unrelated, low-cost items is normal wear. One or two advisories that keep reappearing on the same expensive system year after year is the pattern that actually matters.
Does a past dangerous defect mean the car is a write-off?
No — a dangerous defect is about roadworthiness on the day of testing, not insurance status. It only becomes a write-off concern if the underlying cause was a collision or structural damage, which is a separate check from the MOT record.
Should I trust a seller who calls a major defect 'just a minor thing'?
Verify it yourself rather than taking their word for it. Pull the actual MOT history and check whether the DVSA logged it as major, dangerous, or genuinely minor — the categories are matters of public record, not open to a seller's interpretation.
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