Chapter 1 — What the MOT is, and what it is not

The MOT test is a roadworthiness inspection required by section 47 of the Road Traffic Act 1988. Most cars and light vans must be tested annually once they reach three years old; some vehicles (taxis, ambulances, vehicles with more than eight passenger seats) are tested from one year old. The test is administered by the Driver and Vehicle Standards Agency (DVSA) and carried out at approved testing stations by an authorised tester known as a Nominated Tester.

01What the certificate actually means

An MOT pass certificate confirms that, at the moment of test, the vehicle met the minimum statutory roadworthiness standards set out in the DVSA inspection manual. It is not a mechanical warranty. It does not certify that the car is in good condition, that it will not break down, or that hidden faults are absent. A car can pass on Monday and develop a dangerous fault on Tuesday — the certificate does not become invalid, but the driver is now committing an offence by using the vehicle on the road in that condition.

02The defect categories

Since May 2018 the MOT has used three defect categories, aligned with EU Directive 2014/45. Testers must apply them as written in the inspection manual; they are not a matter of opinion.

• Dangerous. A defect that is a direct and immediate risk to road safety or has a serious impact on the environment. The vehicle fails the test and must not be driven away from the test station. Driving it on the road can attract prosecution.
• Major. A defect that may affect the vehicle's safety, put other road users at risk, or have an impact on the environment. The vehicle fails. It can be driven away only if the current MOT is still valid and the defect is not Dangerous.
• Minor. A defect with no significant effect on safety or the environment. The vehicle passes, but the defect is recorded.
• Advisory. Not a defect under the categories above, but something the tester thinks the owner should be aware of — often a component approaching the limit, such as brake pads at 3mm.

03Who can test, and the audit regime

Only an Authorised Examiner (the business) can hold an MOT testing licence, and only a Nominated Tester (the individual) can carry out the inspection. To become a Nominated Tester an applicant must hold a full UK driving licence for the appropriate class, have at least four years' relevant repair experience, complete a DVSA-approved training course, and pass the DVSA demonstration test. Testers must complete annual training and an annual assessment to keep their authorisation.

The DVSA audits stations through site visits and through automatic data analysis of testing patterns. A tester who consistently passes vehicles that other testers fail, or who completes tests faster than the model time, will attract a review.

04The classes of test

• Class 1 and 2. Motorcycles, with and without sidecars.
• Class 3. Three-wheeled vehicles up to 450kg unladen.
• Class 4. Cars (up to eight passenger seats), light goods vehicles up to 3,000kg design gross weight, and most motor caravans. This is the test most people mean when they say "MOT".
• Class 5. Private passenger vehicles with 13 or more seats.
• Class 7. Goods vehicles between 3,000kg and 3,500kg design gross weight.

The rest of this book deals primarily with Class 4, which covers the overwhelming majority of vehicles tested in the UK. Class 7 is largely the same inspection with weight-related differences in brake testing and tyre load ratings.

05The structure of a test

A Class 4 test is structured around the inspection manual's sections. A competent tester works through them in a consistent order so that nothing is missed. Broadly:

• Identification of the vehicle (registration plate, VIN).
• Lamps, reflectors and electrical equipment.
• Steering and suspension.
• Brakes (visual inspection, then roller brake test).
• Tyres and road wheels.
• Seat belts and supplementary restraint systems.
• Body, structure and general items.
• Exhaust, fuel and emissions.
• Drivers' view of the road.

Each section has its own chapter in this encyclopedia.

06The five misunderstandings owners bring to the test bay

First, that the test covers the engine. It does not. A car with a serious internal engine fault can pass the MOT if emissions are within limits and nothing leaks onto the road.

Second, that the test covers the clutch. It does not. The clutch is not part of the inspection.

Third, that advisories are failures. They are not. An advisory is the tester telling you what to watch.

Fourth, that the certificate is a defence. It is not. The driver and the keeper remain responsible for the condition of the vehicle every time it is used on the road.

Fifth, that a car cannot be driven if it fails. It can, if and only if the previous MOT is still valid, the failure items are not Dangerous, and the driver is not otherwise breaching the Construction and Use Regulations. In practice, almost all owners take the vehicle home for repair before driving it further.

07How to use this encyclopedia

If you own a car: read the chapter that matches the part you are worried about before booking a test, and you will know what the tester is going to look at and what would cause a fail.

If you are studying to become a Nominated Tester: this book is a companion to, not a substitute for, the DVSA inspection manual. Every defect category and method of inspection in this book is drawn from that manual; the manual is the authoritative source and is updated periodically.