Will my brake discs fail my MOT?

Thursday 22nd October 2026

Your brakes are a key part of your MOT, and testers check them for efficiency and safety. This guide explains how your brake discs affect your braking, what testers look for during the test, and the signs that your brake discs may need replacing.

How do brake discs impact braking efficiency?

Brake discs slow and stop your car by turning kinetic energy into heat. Brake pads clamp against your brake disc and creates friction that brings your car to a halt.

 There are several disc conditions that impact braking performance including:

• Thickness: A thicker brake disc absorbs and releases more heat caused by friction. A worn disc heats up faster, but loses friction quicker too. This creates brake fade and increases your stopping distance.
• Surface condition: Brake pads grip best on a flat, smooth surface where the area of the brake pads and disc connection are maximised. Deep scoring, pitting or heavy corrosion reduces the contact area between brake pads and brake disc which reduces overall brake force.
• Disc warp: If the disc is warped and not flat, it will make uneven contact with the brake disc. This creates vibration which can be felt through the pedal and steering wheel. The degree of warp will mean that it your braking force varies with each rotation.
• Contaminants: Oil, grease and brake fluid can impact the friction between the brake pads and discs, resulting in a lower braking force, even with a slight contamination.
• Overheated discs: If your discs over heat regularly, they can develop a hard shiny coating knowing as glazing. When this occurs the pedal may feel firm but the car comes to a stop much slower than it should.
• Uneven wear: If the brake discs on the same axle wear unevenly, one side will end up braking harder than the other. This might mean that your car pulls to one side when braking.

Worn brake discs force the rest of your braking system to work harder, so the loss in brake efficiency increases the longer your brake discs are left unrepaired.

What do testers check on brakes during your MOT?

MOT testers check how efficient your brakes and brake discs are by carrying out a visual inspection with a measured brake check. Testers carry out several checks to ensure your brakes are working as they should be.

1. Roller brake test: The tester drives the car onto a roller brake tester, where each wheel is placed onto a pair of rollers. The tester applies the brakes and the machine measures the braking force for each wheel. It calculates the efficiency as a percentage of the vehicles weight. It allows testers to compare braking power for wheels on the same axle as well as overall braking power.
2. Decelerometer test: Some vehicles are not suitable for the roller brake test, so testers road test the brakes with a decelerometer to measure exactly how quickly the car slows.
3. Disc checks: The tester visually inspects the discs for wear, cracks, scoring corrosion and secure connection. Pads and brake pedal are also checked, without removing the wheels.
4. Warning light check: The ABS and brake warning lights must work and must not stay illuminated during the test.

Brake discs that are significantly worn, loose, cracked or contaminated will result in an automatic MOT fail. Light wear or surface rust will result in an advisory note to monitor or replace them soon.

When do my brake discs need replacing?

Brake discs typically last between 30,000 and 80,000 miles depending on your driving style and road conditions. Brake discs wear every time you stop and are designed to give you a warning before it’s time to replace them. If you notice any of the following symptoms, book a free brake check at Formula One Autocentres and our trained brake specialists will be happy to carry out a full inspection. Signs its time for an upgrade include:

• Vibration or pulsing: A shudder or pulsing sensation means that the brakes are warped or worn.
• Grinding or scraping: A crunching metallic sound means the brake pad is completely worn away causing the metal plate to grind against the brake disc.
• Longer stopping distances: While this may be caused by other worn brake components, it can also be caused by worn brake discs.

How can Formula One Autocentres help?

If your brake discs are showing signs of wear or if you have any concerns about your brakes, book a free brake check, and our team will advise any work that needs to be done. When it’s time to book  your MOT, find your nearest testing station and save when you book together with a full service.