In short
Until 19 May 2018 an item on a British MOT either failed or it did not. A fail carried no grade, and calling a defect dangerous was left to the tester's opinion.
Since 20 May 2018 every defect wording has had a fixed grade: dangerous or major, which fail, or minor, which passes. Advisories continue alongside.
An old fail cannot be converted into a grade. Some would be dangerous today, most would be major, and some would be minors that pass.
Any car first tested before 2018 has a history written under two sets of rules. GOV.UK holds results for cars back to 2005, so on older stock the earlier scheme can cover ten years or more of the record. In a sample of 3,675 vehicles from DVSA's bulk data that we examined in October 2026, about 18% of all recorded defects dated from before the change. The comparison here covers England, Scotland and Wales. GOV.UK's own announcement notes: "The MOT test works differently in Northern Ireland."
The two schemes side by side#
| Until 19 May 2018 | From 20 May 2018 | |
|---|---|---|
| Outcome for a defect | Fail. Lesser items could be given as advisories | Dangerous or major (fail), or minor (pass). Advisories remain |
| Who decides that a defect is dangerous | The tester, as an opinion noted on the refusal or advisory notice | DVSA, in advance, for each defect wording |
| Defects short of a fail | No category. Good practice was to advise on items "near to, but which have not yet reached the point of test failure" | Minor defects, which the tester must record where they apply |
| Documents | VT20 certificate, VT30 refusal notice, VT32 advisory notice | A redesigned certificate that "lists any defects under the new categories" |
| Inspection manual | Nine sections, beginning with lamps | Sections 0 to 10, beginning with identification of the vehicle |
| Reference at the end of a history line | (4.1.E.1), (3.5.1g) | (5.2.3 (e)), (1.1.13 (a) (ii)) |
| European basis | Directive 2009/40/EC | Directive 2014/45/EU |
The left-hand column quotes the inspection manual in its April 2013 issue, the most recent copy of the old manual we could find. GOV.UK now hosts only the current manual, so the old wording may have been revised between that issue and 2018.
Why the test changed#
The change gave effect to Directive 2014/45/EU, which set common minimum rules for roadworthiness testing and required defects to be graded by severity. In Great Britain it was brought in by the Motor Vehicles (Tests) (Amendment) Regulations 2017, in force from 20 May 2018. GOV.UK announced five changes: the defect categories, stricter rules for diesel emissions, some new items in the test, a new certificate, and an exemption for vehicles over 40 years old that have not been substantially changed.
The old scheme left the gravest judgement to the individual tester. DVSA described the position a month before the change: "Testers can then mark defects they believe are dangerous, and make the vehicle owner aware." The old manual put the matter in terms of opinion: "If in the opinion of the NT the vehicle has a dangerous defect this must be recorded in box C of the VT30 or in box C of the VT32 as appropriate." (NT stands for nominated tester.) From 20 May 2018 the new rules would, DVSA said, "pre-define what is considered as 'dangerous'", with every other failure item called major. The agency gave its reason in the same article: "Moving to pre-defined dangerous defects will bring consistency to what is recorded as dangerous."
The scheme has outlasted the United Kingdom's membership of the European Union. The current manual, last updated on 1 June 2026, still grades every defect as dangerous, major or minor.
What an old fail became#
An old fail has no grade, and DVSA has never published a table that converts old defects into new ones. The pairings below are ours, made by setting the old manual's wording against the current manual's.
| Defect | Until 19 May 2018 | From 20 May 2018 |
|---|---|---|
| Tyre tread below 1.6mm | Fail (4.1.E.1) | Dangerous (5.2.3 e) |
| Brake pad less than 1.5mm thick | Fail (3.5.1g) | Dangerous (1.1.13 a ii) |
| Brake fluid below the minimum mark | Fail (3.6.G.1b) | Minor (1.1.10 d i) |
| Brake fluid warning lamp illuminated | Fail (3.6.G.2) | Minor (1.1.10 f) |
| One of two number plate lamps not working | Fail | Minor (4.7.1 b i) |
| Tyre obviously under-inflated | Not a failure. Under-inflation was "not in itself a reason for rejection" | Minor (5.2.3 l) |
| Reversing lamp inoperative | Not tested | Major (4.6.1 a), on vehicles first used from 1 September 2009 |
| Brake fluid contaminated | Not tested | Major (1.8 a) |
| Visible smoke from a diesel fitted with a particulate filter | No such defect | Major (8.2.2.2 d) |
The first two rows are the reason an old fail should not be read as a major. The measured limits for tread and pad thickness did not move in 2018, and both now carry the top grade. The next three rows run the other way. DVSA's guidance to testers at the time, since withdrawn, listed the "defects that no longer cause an MOT test fail": brake fluid level below the minimum mark, a brake fluid warning lamp illuminated or inoperative, power steering fluid below the minimum mark, an insecure trailer electrical socket, the direction indicator flashing rate, one of two registration plate lamps missing or inoperative, several audible warning defects, and "many items 'insecure' but not likely to become detached".
Our own matching of the two defect tables that DVSA publishes with its open data gives a sense of proportion. The pre-2018 table holds 2,388 entries that apply to cars and the current one 1,862. Only 523 of the old entries survive with essentially the same wording. Of those, about 84% are now majors, 9% are minors and 7% are dangerous. A further 844, roughly a third, have no confident match in the current table at all. The matching is ours and approximate, and the result is the basis of the pre-2018 defects list, which says what each old part is called now wherever that can be established.
What was added, tightened and removed#
New items#
The GOV.UK announcement listed the additions: tyres that are obviously under-inflated, contaminated brake fluid, fluid leaks posing an environmental risk, brake pad warning lights and missing pads or discs, reversing lights and headlight washers on vehicles first used from 1 September 2009, and daytime running lights on vehicles first used from 1 March 2018. They are not all failures. An under-inflated tyre is a minor, and since March 2022 the manual has carried the sentence "An illuminated brake wear indicator is not a reason for failure."
Diesel emissions#
Two defects were created for diesels fitted with a particulate filter: visible smoke of any colour from the exhaust, and evidence that the filter has been tampered with. Both are majors. The smoke limit also became the value on the manufacturer's plate where there is one, with a lower default of 0.7m-1 for vehicles first used on or after 1 January 2014.
DVSA reported that 238,971 diesel cars failed the emissions test between 20 May and 19 November 2018, against 58,004 in the same period of 2017. Petrol cars rose from 292,468 to 505,721. The release does not say which defects were counted, and the new test included emission checks that had not existed a year earlier, so the two periods are not like for like. The overall failure rate hardly moved: 33.2% for diesel cars against 33.8% in 2017, and 34.7% for petrol against 35.7%.
Removed, and partly restored#
The May 2018 manual dropped the failure for a space-saver wheel fitted as a road wheel, the comparison of tyre structure between axles, and the checks on tyre valves and on tyres seated correctly on the rim. The last two did not stay out for long. DVSA revised the manual on 13 September 2018 in response to feedback from testers, and a seriously damaged tyre valve returned as a dangerous defect and an incorrectly seated tyre as a major. Tests carried out between 20 May and 12 September 2018 were therefore graded under a slightly different table from those that followed.
The 40-year exemption#
Until the change, only vehicles first built before 1960 were exempt from the test. Since then a vehicle has ceased to need an MOT from the 40th anniversary of its registration or manufacture, provided it has not been substantially changed. The history of an older classic may stop for that reason.
Did the change alter the failure rate?#
DVSA's MOT testing data for classes 3 and 4 (cars, vans and passenger vehicles with up to 12 seats) gives the initial failure rate for each financial year.
| Financial year | Initial failure rate |
|---|---|
| 2013 to 2014 | 40.00% |
| 2016 to 2017 | 35.40% |
| 2017 to 2018, the last full year of the old scheme | 34.50% |
| 2018 to 2019, covering both schemes | 33.60% |
| 2019 to 2020, the first full year of the new scheme | 31.69% |
| 2024 to 2025 | 28.08% |
The rate fell across the change. It had also been falling for years beforehand, and it is lower again today. The figures give no ground for crediting the new scheme with the decline. DVSA also splits 2018 to 2019 at the changeover: 34.90% of tests failed initially between 1 April and 19 May 2018, and 33.40% between 20 May 2018 and 31 March 2019. Those two periods cover different months of the year.
What the new scheme did produce is a measure that had not existed. Between 20 May 2018 and 31 March 2019, 9.40% of tests recorded at least one dangerous defect. In the year to March 2025 the figure was 7.70%. DVSA's breakdown by defect category cannot be compared across the change, because it follows the old manual's headings before 20 May 2018 and the new manual's afterwards.
How each scheme looks in an MOT history#
GOV.UK's MOT history service marks the boundary with a notice between the last test under the old scheme and the first under the new. It is headed "The MOT test changed on 20 May 2018" and reads: "Defects are now categorised according to their severity - dangerous, major, and minor."
| Tests until 19 May 2018 | Tests from 20 May 2018 | |
|---|---|---|
| Headings on a failed test | "Reason(s) for failure" and "Advisory notice item(s)" | "Do not drive until repaired (dangerous defects)", "Repair immediately (major defects)", "Repair as soon as possible (minor defects)" and "Monitor and repair if necessary (advisories)" |
| Example line | Parking brake: efficiency below requirements (3.7.B.7) | Rear Brake pad(s) less than 1.5 mm thick (1.1.13 (a) (ii)) |
| In DVSA's data | A generic FAIL, with a separate flag where the tester marked the defect dangerous | DANGEROUS, MAJOR or MINOR |
Five points follow for anyone reading across the boundary.
- Judge an old fail by its wording. A tread or pad-thickness fail from 2015 describes the condition that is graded dangerous today, and a brake fluid level fail from the same year describes a minor.
- Do not count fails across the boundary as like for like. Items that fail a car in 2016 may appear as minors on a pass in 2019, and a 2019 test can fail on a reversing lamp or contaminated brake fluid that no 2016 test examined.
- Treat the reference in brackets as a pointer to the manual. It is printed on advisories as well as failures in both schemes, so the heading above the line gives the outcome and the reference does not.
- Read the summer of 2018 with the September revision in mind. A handful of defects changed grade or reappeared on 13 September 2018.
- Expect the absence of a dangerous marking on old tests to mean little. Before the change it depended on whether the individual tester chose to record one.
What the grades do and do not say about risk on the road is the subject of MOT defect severity vs real-world risk, and how to read an MOT history covers mileage, gaps and repeat advisories. The current MOT defects list gives every wording now in use with its grade.
Dabers ANPR shows the whole record, old scheme and new, without leaving the listing. Right-click a car photo and the DVSA history opens on the same page, with every test, mileage reading, advisory and failure. How it works explains the steps and pricing sets out the cost per check.
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