MOT Advisories: What Actually Happens Next, From 200 Million Tests
A car that passes its MOT with an advisory is 1.6 times more likely to fail its next MOT than one that passes clean. Thirty-one per cent against twenty. Stack up six or more advisories and the failure rate reaches 42%, while the odds of the car disappearing from the record altogether triple.
Those figures come from the DVSA’s published MOT record for every light vehicle in Britain: 138 million cars and vans, 906 million tests, followed from one passing test to the next. So far as we can tell, nobody has measured this before.
Here is what MOT advisories actually mean for your car: how MOT advisories and failures differ, which issues need attention now, and which you can safely leave.
Your car passed. Then the tester handed you a certificate with a list underneath it: nearside front worn close to the minimum tread depth, oil leak but not excessive, worn brake pads. Nobody made you fix anything. Nobody told you when to.
Every guide on the subject, including the good ones from the RAC and Halfords, has MOT advisories explained in general terms: an advisory is an early warning about issues that could become a problem. None of them could tell you how often they do. That’s the gap this fills.
What an MOT advisory actually means
An advisory is a note from the MOT tester about something not bad enough to fail an MOT but heading that way. An advisory is not an MOT failure and it carries no legal force. Your MOT certificate is valid, your car is roadworthy, and you can drive away.
The most common MOT advisories are ordinary wear and tear: tyre tread getting low, worn brake pads, suspension bushes and light corrosion.
MOT defect categories explained
Since May 2018 the MOT test has recorded defects in three categories.
- Dangerous and Major both fail the test.
- Minor does not. Your car passes, but the fault goes on the record.
- Advisories sit alongside those.
The distinction people usually miss is that a minor defect is something wrong now, while an advisory is something expected to go wrong in future. Both appear in your MOT results, and both stay visible on your car’s record for anyone who checks its MOT history later.
There’s a fourth outcome you might see on an older certificate. PRS, or pass after rectification at station, means the car failed, the garage fixed it there and then, and it passed before you collected it. The work was still needed.
Why two testers might not agree
Whether you get an advisory at all is partly down to the individual doing the test. DVSA’s own guidance is explicit that advisories are a non-mandatory part of the MOT test and it’s up to them to decide whether to advise on an item. Some garages have a house policy.
Whoever tests it next will often re-examine previous advisories to see whether anything has moved, which means a fault flagged once tends to stay visible year after year. That variation is real, and worth holding in mind before you read too much into a single advisory on a single certificate.
Do MOT advisories matter? The numbers say yes
Yes, measurably. We looked at 200 million passing tests from 20 May 2018 onwards and followed every vehicle to its next annual MOT.
| At the passing test | Tests | Failed the next MOT |
|---|---|---|
| Passed clean | 123,752,151 | 20.0% |
| Passed with an advisory | 76,550,749 | 31.2% |
Eleven percentage points is a bigger gap than we expected, and it settles something service advisors have believed for years without being able to prove it. Roughly one in three cars that passed its MOT with an advisory fails the next one, against one in five that didn’t.
Advisories do not change the certificate you’re holding. They change the odds on the one you’ll need next year.
What happens when many advisories stack up
The single contrast isn’t the interesting part. This is:
| Advisories at the passing test | Failed the next MOT | Never came back at all |
|---|---|---|
| 0 | 20.0% | 3.3% |
| 1 | 28.4% | 4.2% |
| 2 | 29.5% | 4.4% |
| 3 | 34.3% | 6.1% |
| 4 | 34.5% | 6.5% |
| 5 | 39.0% | 8.4% |
| 6 or more | 42.0% | 10.5% |
The failure rate climbs at every step. That matters more than the headline, because a single cherry-picked comparison can be a fluke and a clean monotonic gradient across seven bands can’t.
And look at the right-hand column. A car with six or more MOT advisories is three times more likely to disappear from the MOT record entirely than a clean one. Those cars weren’t repaired and they weren’t failed. They were scrapped, exported or taken off the road. Advisories don’t just predict a fail. They predict the end of the car.
Which advisories actually turn into failures
Not all of them are worth the same, and the most common ones are not the most serious. We matched each advisory to its defect code, never to the tester’s wording, because codes are stable and phrasing isn’t, then checked whether the same fault failed the same vehicle at its next test.
| Defect code | What it is | Advisories followed | Became a failure |
|---|---|---|---|
| 2.1.3 | Track rod end ball joint has play | 1,440,628 | 16.2% |
| 5.3.4 | Suspension arm pin or bush worn | 13,902,722 | 12.6% |
| 1.1.11 | Brake pipe corroded | 6,608,177 | 9.7% |
| 5.2.3 | Tyre worn close to the legal limit | 53,052,067 | 8.5% |
| 1.1.13 | Brake pads wearing thin | 12,622,432 | 6.3% |
| 1.1.14 | Brake disc worn or scored | 16,935,072 | 3.1% |
| 8.4.1 | Oil leak, but not excessive | 4,793,386 | 1.0% |
Group those by section of the inspection manual and the pattern is sharper still.
| Section of the test | Advisories followed | Became a failure |
|---|---|---|
| Steering | 2,186,039 | 11.5% |
| Axles, wheels, tyres, suspension | 83,512,219 | 8.6% |
| Lamps and electrical | 2,746,697 | 6.8% |
| Body and structure | 4,477,678 | 6.4% |
| Brakes | 41,637,168 | 5.5% |
| Emissions and leaks | 5,286,558 | 1.1% |
| Visibility | 117,662 | 0.9% |
What these advisories indicate
Steering is the risk, because the wear is already moving. A track rod end with play converts at 16.2%, the highest rate of anything we measured, and worn suspension bushes aren’t far behind at 12.6%. Neither is a wear item you can watch and top up. Both have a countdown already running.
Tyre wear is the volume. Fifty-three million advisories on one code, more than a quarter of every advisory we followed. Tread goes down at a predictable rate, and rubber flagged as close to the minimum has, at best, a year in it before the tyres need to be replaced.
The advisories you can leave
An oil leak described as not excessive becomes a failure 1% of the time. That’s the one advisory on the list you can genuinely park, and it’s also the one most likely to worry a driver who doesn’t know the numbers, because oil on a driveway looks alarming and a worn ball joint doesn’t look like anything.
Brake discs recorded as worn or scored convert at 3.1%, which is lower than most people assume for anything with the word brake in it.
Longer gaps convert more, which is what you’d expect if these are wear items rather than random breakages. An advisory followed 321 to 400 days later becomes a failure 7.2% of the time. At 501 to 800 days it’s 8.3%.
Can you drive with MOT advisories?
Yes. An advisory has no legal weight. You still hold a valid MOT, and neither the police nor your insurer will treat the certificate as anything other than a pass. Nothing stops you driving with MOT advisories on the record for as long as the certificate runs.
Two caveats worth knowing, though.
An advisory means the item was legal on the day of the test. It doesn’t mean it’s still legal now. Rubber advised in March can be under 1.6mm by August, and at that point it’s three penalty points and a fine for each one, regardless of what the certificate says.
And the tester wrote it down for a reason. They had the car on a ramp with the wheels off the ground. You don’t.
How to fix advisories in the right order
Sort by what the data says converts, not by what sounds frightening. Not every advisory needs fixing this month. A couple of them need doing now.
- Steering and suspension. Track rod ends, ball joints, suspension arm bushes. Highest conversion rate of anything we measured, no way to monitor them yourself, and they need attention soonest because they become a genuine safety risk as they worsen, affecting how the car handles long before they fail a test.
- Corroded brake pipes. Nearly one in ten becomes a failure, and corrosion only goes one way.
- Tyres. Not because they convert fastest but because they’re the only item on the list with a legal limit you can be prosecuted for, and because you can check tyre tread depth yourself in two minutes with a 20p coin.
- Brake pads and discs. Genuine wear items with a predictable life. Worth pricing up as a planned repair at your next service rather than treating as urgent.
- Oil leaks described as not excessive. Keep an eye on the level. Mention it at the next service.
If your car needs the same work two years running, treat that differently from a new note. Repeated advisories mean the wear is continuing and nobody has touched it, and an advisory often reappears on a future MOT in exactly the words it did last time. Addressing advisories early is cheaper than addressing them at 8am on the morning your MOT is due, when the car is already in the bay and the part is on a two-day lead time.
Buying or selling a car with MOT advisories
Anyone can check its MOT history free on the gov.uk service using nothing but the registration. It’s the only free MOT checker that comes straight from the DVSA record, and it shows every advisory a vehicle has ever collected.
Buying a used car
Choose to buy a car with MOT advisories against it by all means. Just do the check first.
Buying a car with MOT advisories on file is normal, and a clean sheet isn’t what you’re after. Almost no ten-year-old car has one. You’re looking for three things: recurring advisories year after year, which say the seller has been ignoring them; corrosion advisories, which get worse and more expensive to repair; and a mileage history that doesn’t climb steadily.
A car with two fresh advisories and a consistent service pattern is usually a better buy than one with none and a suspicious four-year gap.
If you plan to sell your car
Your buyer can see everything you can. A couple of hundred pounds of repair work before you list removes the most obvious lever they have to negotiate with. It also helps keep your vehicle looking like one that’s been maintained rather than one nursed to the next test.
What this means if you run a garage
Every service advisor has had the conversation where a customer decides an advisory can wait. Now there’s a number to put behind the repair recommendation, and it isn’t a sales line, it’s the national record.
Roughly one in three of those cars fails its next MOT. Where six or more advisories are stacked up, one in ten never comes back at all.
That second figure is the one worth sitting with. A car that vanishes from the record is a customer who has gone, and the data says advisories are the early signal. The vehicle that comes back next March with a fistful of amber items is telling you something about the year after that.
Which is a retention problem before it’s a workshop problem. Torqueflow puts reusable checklist templates on the job card so the same inspection runs the same way every time, keeps findings with photos attached to the vehicle rather than on a scrap of paper, and lets a customer approve a severity-badged quote in their own portal instead of playing phone tag from a work car park. MOT reminders go out automatically at sixty, thirty, fourteen and seven days, so nobody has to remember who is due to book an MOT next month. Book a demo if the advisory conversation is one your team keeps losing.
MOT advisories: common questions
How we worked this out
The source is the DVSA MOT history bulk dataset: 138.0 million vehicles, 906.5 million tests and 1.89 billion individual defect items, covering every light vehicle test in Great Britain and Northern Ireland from 2005 to 29 August 2026.
Five decisions shaped the numbers, and each is a place the analysis could have gone wrong.
- Retests are excluded. Ninety-two per cent of tests taken after a failed MOT happen within ten days and pass 99 times out of 100, because they’re the same car coming back from the workshop. Counting those as the next MOT would have made every rate meaningless. The next annual test is the first one at least ninety days later.
- Cars that never returned are bounded, not dropped. Some vehicles disappear from the record and we can’t know whether they’d have passed. Counting every one of them first as a pass and then as a fail gives a range of 19.3% to 23.0% for clean passes and 29.3% to 35.4% for advisory passes. Those ranges don’t overlap, so the conclusion holds at either extreme. Quietly dropping them would have flattered the advisory group, because a scrapped car is the worst outcome there is.
- Only tests from 20 May 2018 count. The inspection manual was renumbered that day, so earlier defect codes aren’t comparable.
- 81.5% of advisories carry a code. The rest is tester free text, things like “nail in tyre”, which can’t be followed item to item. The per-code table covers the coded share. The headline doesn’t depend on it.
- An MOT is a roadworthiness inspection, not a reliability survey. A mechanic will check tyres, brakes, steering, suspension, corrosion and lights. The test says nothing about your gearbox, your engine or anything repaired beforehand. This measures how a car survives contact with British roads, which is a narrower thing than how reliable it is.
The dataset carries no postcode and no test station, so we can’t break any of this down by region or compare one garage against another. Nobody can. That information doesn’t exist in any DVSA product.
Contains public sector information licensed under the Open Government Licence v3.0.
