MOT advisory codes explained
Most defects and advisories on an MOT end with a reference in brackets, such as (5.2.3 (e)) or (1.1.11 (c)). These are not random. They point to the exact rule in the official MOT inspection manual that the tester used. Once you know how to read them, you can tell at a glance which part of the car the note is about.
How to read an MOT code
Take 5.2.3 (e) as an example:
| Part | Meaning | Example |
|---|---|---|
| 5 | Section of the manual | Axles, wheels, tyres and suspension |
| 5.2 | Component group | Wheels and tyres |
| 5.2.3 | Specific item | Tyres |
| (e) | The defect within that item | Tread depth does not meet the requirements |
Some codes have a further number in brackets, such as (d) (ii), which narrows it down again to a specific version of the defect.
The 11 sections of the MOT inspection manual
| Code starts with | Section | Typical items |
|---|---|---|
| 0 | Identification of the vehicle | Registration plates, VIN |
| 1 | Brakes | Pedal, servo, pipes, hoses, discs, pads, performance |
| 2 | Steering | Steering rack, joints, column, power steering |
| 3 | Visibility | Windscreen, wipers, washers, mirrors, driver's view |
| 4 | Lamps, reflectors and electrical equipment | Headlamps, indicators, stop lamps, wiring, battery |
| 5 | Axles, wheels, tyres and suspension | Tyres, wheels, bearings, springs, shock absorbers, bushes |
| 6 | Body, structure and attachments | Corrosion, structure, doors, seats |
| 7 | Other equipment | Seat belts, airbags and other fitted equipment |
| 8 | Nuisance | Noise, exhaust emissions, fluid leaks |
| 9 | Supplementary tests for buses and coaches | Bus-specific items |
| 10 | Seat belt installation checks | Extra checks for some passenger vehicles |
Section 1: brakes
| Code | Item |
|---|---|
| 1.1 | Condition and operation of the braking system |
| 1.1.10 | Brake servo units and master cylinder |
| 1.1.11 | Rigid brake pipes |
| 1.2 | Service brake performance and efficiency |
| 1.3 | Secondary brake performance and efficiency |
| 1.4 | Parking brake performance and efficiency |
Common example: “Brake pipe slightly corroded (1.1.11 (c))” refers to rigid brake pipes. Testers reject a pipe when chafing, corrosion or damage has reduced the wall thickness by about a third. Slight surface corrosion is given as an advisory so you can keep an eye on it.
Section 4: lamps, reflectors and electrical equipment
| Code | Item |
|---|---|
| 4.1 | Headlamps (4.1.2 is headlamp alignment) |
| 4.2 | Front and rear position lamps and daytime running lamps |
| 4.3 | Stop lamps |
| 4.4 | Direction indicators and hazard warning lamps |
| 4.5 | Front and rear fog lamps |
| 4.6 | Reversing lamps |
| 4.7 | Rear registration plate lamps |
| 4.8 | Rear reflectors |
| 4.9 | Tell-tale (warning) lights for lighting equipment |
| 4.10 | Trailer electrical socket |
| 4.11 | Electrical wiring |
Common example: “Headlamp aim too high (4.1.2 (a))” refers to headlamp alignment. It is a quick, cheap fix at most garages. Lighting faults are the most common reason cars fail the MOT.
Section 5: axles, wheels, tyres and suspension
| Code | Item |
|---|---|
| 5.1 | Axles, stub axles and wheel bearings |
| 5.2.1 | Road wheel and hub |
| 5.2.2 | Road wheel condition |
| 5.2.3 | Tyres |
| 5.3.1 | Springs |
| 5.3.2 | Shock absorbers |
| 5.3.3 | Suspension arms, rods, struts, sub-frames and anti-roll bars |
| 5.3.4 | Suspension joints, pins and bushes |
| 5.3.5 | Gas, air and fluid suspension |
Tyre codes under 5.2.3
| Code | Defect | Category |
|---|---|---|
| 5.2.3 (a) (i) | Load capacity or speed rating below the minimum | Major |
| 5.2.3 (a) (ii) | Load capacity not enough for the weight on the axle | Dangerous |
| 5.2.3 (b) | Different tyre sizes on the same axle | Major |
| 5.2.3 (c) | Different tyre structures on the same axle | Major |
| 5.2.3 (d) (i) | Cut deep enough to reach the ply or cords | Major |
| 5.2.3 (d) (ii) | Lump, bulge or tear from structural failure, with cords exposed or damaged | Dangerous |
| 5.2.3 (e) | Tread depth below the legal requirement | Dangerous |
When a tyre is close to, but not below, a limit, the tester can record the same code as an advisory, such as “Tyre worn close to legal limit (5.2.3 (e))”. That is why you will often see the code on a pass.
Advisory vs defect with the same code
The code tells you what was looked at. The category tells you how bad it was. The same code can appear as an advisory one year, a minor defect the next and a major defect the year after if the problem gets worse. Following one code across several MOTs is a good way to see whether a fault is being dealt with. MOTstory groups these as repeat advisories.
Looking up any code
- Note the full code, for example 5.3.4 (a) (i).
- Use the first number to find the section in the table above.
- Open the matching section of the official MOT inspection manual on GOV.UK to read the exact rule and what the tester checks.
Older MOT records from before May 2018 often show references in a different format, because the manual was restructured when the dangerous, major and minor categories were introduced.