What MOT Advisories Mean (and Which Ones Matter)

What an advisory actually is

During an MOT the tester works through well over a hundred items. Anything that fails the legal standard is recorded as a defect. Anything that passes but is on its way to failing — a tyre with 2.5mm of tread left, a brake disc that's worn but still within limits, a bit of surface rust on a sill — is recorded as an advisory.

Advisories are the tester's professional opinion. They are not a legal defect, there is no deadline to fix them, and you won't be stopped for driving with one. But they are public: every advisory since 2005 sits on the national MOT record and shows up on any free MOT history check.

Advisory, minor, major, dangerous

Since May 2018 MOT faults have been graded. The wording matters when you're reading a history.

A car can pass with a page of advisories and minors. That's not necessarily bad — but it's not free, either.

The advisories that cost the most

Not all advisories are equal. “Nearside front tyre worn close to legal limit” is a small job. “Corrosion to front subframe” can be four figures. The ranges below are the same typical ranges the free check uses, from the cheapest realistic outcome to the worst case for that area — where a car lands depends on the make, the wording and how many items sit together.

• Tyres near the limit — typical range £60–£300. Two or more at once is a bill to price in before you make an offer.
• Brake discs and pads wearing — typical range £80–£400. Almost always accurate; discs don't un-wear.
• Corrosion — typical range £120–£1,200, and the wording is everything. Surface corrosion on a sill or spring is cosmetic. Corrosion “within a prescribed area” of a suspension mount, or anything described as structural, is a welding job and will usually be a major next year.
• Suspension bushes, drop links, ball joints, shock absorbers — typical range £80–£800. Cheap parts individually, but three of them on one axle usually means the whole corner is tired. A shock absorber with light misting is usually fine for another year; a leaking one is a fail-in-waiting.
• Oil or fluid leaks — typical range £100–£1,500. “Slight” is normal on an older engine. “Excessive”, or any leak near the brakes, needs a proper diagnosis before you buy.
• Exhaust — typical range £80–£700. A “slight blow” tends to become a major within a year.

You don't have to price each line yourself. The free check reads the current advisories and turns them into a repair cost estimate for the car in front of you.

Repeat advisories: the deferred-maintenance signal

One advisory tells you about a part. Three years of the same advisory tells you about the owner.

If “front brake discs worn, pitted or scored” appears in 2023, 2024 and 2025, nobody has replaced the discs. The car passed each time, so the owner didn't have to. When you buy it, you inherit the bill — and probably a few others that never made it onto the certificate.

A couple of things to watch when you're counting:

• A fail followed by a retest a few days later is one event, not two. The advisory on the retest is the same advisory.
• A streak that ended years ago isn't a current problem. If the disc advisory ran 2019–2021 and hasn't appeared since, someone fixed it.
• The same wording on different items is normal. “Tyre worn close to legal limit” every year on different corners just means the car is driven.

Advisories that aren't really faults

Testers also record observations that aren't defects at all:

• “Undertray fitted, obscuring some components”
• “Non-standard wheels fitted”
• “Vehicle has been modified”
• “Engine cover obscuring components”

These are descriptive. They tell you the tester couldn't see something, not that it was wrong. When AI Plate Checker reads a history it lists these separately as tester notes rather than as problems to fix, so a car with a plastic undertray isn't treated as a car with a fault.

Using advisories when you negotiate

The advisories list is the cheapest leverage you'll get. A realistic way to use it:

1. Pull the MOT history before you view the car.
2. Price the current advisories. Add the repeat ones that have never been fixed.
3. Ask the seller which have been done and for the receipts.
4. Whatever hasn't been done comes off the asking price — not the full retail cost, but enough that you're not paying twice.

Sellers who've had the work done will have paperwork. Sellers who haven't will usually say “it's only an advisory”. Both answers tell you something. The used car buying checklist covers what else to ask on the day.

What advisories can't tell you

An advisory history is about wear, not about the car's past. It won't show an insurance write-off, outstanding finance, a stolen marker or how many keepers it's had. For that you need the Full History Report — £9.99, one-off, no subscription, 60 days' access. Like every history check, it reports what the records hold; no check can guarantee a car's past.