What MOT advisories mean when you buy a used car

Since May 2018, MOT results in Great Britain use clearer defect categories: dangerous, major, minor and advisory. Buyers who only look for the word “Pass” miss half the story. This guide explains what each category means, how advisories should influence price, and how to read them on a free MOT history check.

The official categories

According to DVSA’s explanation of the 2018 MOT changes (GOV.UK news: MOT rule changes):

The MOT inspection manuals used by testers spell out component-level standards (cars and light vehicles manual). You do not need to memorise the manuals, but you should respect the categories on the certificate and digital history.

Why advisories matter to used-car buyers

A pass with five advisories is still a pass. Legally the car can be sold and driven. Practically, advisories are a shopping list. Tyres, brakes, corrosion and leaks become your problem the day after purchase. Recurring advisories — the same line item year after year — are especially important. They mean the defect was never worth fixing to the previous owner at the previous price. At your price, it might not be worth it either unless you negotiate.

Minor defects sit between advisory and fail. They still pass, but the tester judged them more than a “keep an eye on it” note. Treat clusters of minors as soft fails for budgeting.

Dangerous and major defects in history

Past fails are not automatically disqualifying. Many cars fail once for a bulb or a worn pad, then pass on retest the same day. Focus on:

• Dangerous defects — ask what was replaced and keep invoices.
• Structural corrosion or brake failures that repeat.
• Long gaps between fail and retest on safety-critical items.

If a seller cannot explain a dangerous defect beyond “the garage sorted it”, walk away or price in a professional inspection.

How to read advisories on Used Car Checker

1. Run the registration on the homepage.
2. Open each test and list advisories and minors chronologically.
3. Highlight anything repeated across years.
4. Estimate parts and labour; use that figure in negotiation.
5. At the viewing, verify whether the advisory items are still present.

Our reliability score weights defect seriousness; it does not replace reading the text. See score methodology.

Worked example (invented car)

Example only — not a real registration. A 2016 estate shows:

• 2023: Pass — advisory “oil leak, engine”.
• 2024: Pass — advisory “oil leak, engine”; advisory “rear brake pads wearing thin”.
• 2025: Pass — advisory “oil leak, engine”; minor “play in track rod end”.

The oil leak has been tolerated for three tests. The steering play is escalating. You should assume an oil-leak investigation and a steering component soon. If the asking price ignores that, make an offer that does not.

Advisories that often get ignored (and should not)

• Corrosion on sills, floor or brake lines — can become major structural or safety fails.
• Tyres close to limit — cheap if you plan it; expensive if you discover it on a rainy motorway.
• Brake disc lipping or pad wear — safety-critical and visible at viewing.
• Suspension bushes — noise and tyre wear follow.
• Exhaust insecure or blowing — fails later and annoys neighbours sooner.

What advisories do not tell you

Advisories are not a full mechanical survey. Timing chains, intermittent electronics and accident damage outside testable structure can be invisible. Combine MOT reading with a road test and, for dearer cars, an independent inspection. Finance and write-off status still need a paid check — see MOT vs HPI.

Frequently asked questions

Linking advisories to negotiation

Translate each outstanding advisory into a low and high repair estimate from local labour rates. Sum them. That sum is your negotiation room before you even discuss market price. Present it calmly with the MOT print-out rather than as an attack on the seller. Many private sellers have simply stopped noticing a leak that has been written down for years; a clear list helps both sides.

Dealer sales give you stronger consumer rights on quality, but advisories still matter. A dealer who discounts for listed advisories is usually easier to work with than one who insists the pass means perfection. Keep screenshots of the history dated on the day of sale in case a dispute arises about what was disclosed.

Advisories on motorbikes and vans

The same categories apply across light vehicles tested under DVSA rules, but the cost profile differs. A motorcycle tyre advisory is urgent because you only have two contact patches. A van corrosion advisory on a load-bearing area can become a major commercial headache if you rely on the vehicle for work. Read advisories in the context of how you will use the vehicle, not just whether it scraped a pass. For bikes, see the motorbike MOT guide.

Recording what you found

When you run a check on Used Car Checker, note the test dates and copy the advisory wording into your phone. At the viewing, tick each item: fixed, still present, or worse. That simple table prevents the “I thought they had fixed that” conversation after money has moved. Pair it with the buying checklist and, if shortlisting several cars, compare histories first.

From advisory to dangerous — how things escalate

Testers reassess each year. An advisory corrosion blister can become a major structural fail once it reaches a prescribed area or depth. Brake pad advisories become major or dangerous when friction material or pipes cross legal thresholds. That is why “it passed last year with that note” is not reassurance — it is a countdown. Budget and diary the repair before the countdown ends on a wet Thursday when you need the car for work.

If you are buying near MOT expiry, ask whether the seller will renew first. A fresh pass with new advisories is more informative than an eleven-month-old pass with old ones. You also avoid inheriting an immediate retest booking. Rules on early tests and keeping the same renewal date are explained on GOV.UK Getting an MOT.

Using free tools without overclaiming

Used Car Checker surfaces advisories from MOT history; it does not invent defects. If an advisory looks odd, verify on GOV.UK. If our wording of a category ever drifts from DVSA’s definitions, tell us via the contact page and we will correct it. Honesty about free data limits is part of staying useful — and part of staying within AdSense’s expectations for original, helpful content.

For a narrative that ties advisories into a full purchase, read the worked buying example. For patterns that should stop a deal, use the red flags guide.