Brakes and the MOT: What Testers Check

How the MOT Tests Your Brakes

The MOT tests your brakes for performance and for condition. The car is driven onto a set of rollers that measure the braking force at each wheel. The tester checks the overall efficiency, the balance between the two sides and the state of the brake parts. Brakes are one of the most safety critical parts of the whole test.

The performance side looks at how well the brakes actually slow the car. As a general guide the service brake, the one you press with your foot, needs around 50 per cent efficiency, while the parking brake needs around 16 per cent. The exact figures vary by vehicle, though the principle is the same. Our guide on What an MOT Checks lists all the areas a tester inspects.

The condition side looks at the parts themselves, from the pads and discs to the pipes, hoses and fluid. A brake that performs adequately on the day can still fail if a part is badly worn or a pipe is corroded, since that is a fault waiting to happen.

How Brakes Are Measured

Most cars have their brakes tested on a roller machine, which gives an accurate reading of the force at each wheel. The table below sets out what the test is looking for.

A large imbalance between the left and right of an axle can fail even if the overall figure looks acceptable, since uneven braking is dangerous. Our guide on Top Reasons Cars Fail MOT covers the other common failure areas alongside brakes.

What Makes Brakes Fail an MOT

Several brake faults will fail the test, covering both how the brakes perform and the condition of the parts. Knowing them helps you spot a problem before the test.

Many of these show warning signs you can notice in everyday driving, such as a spongy pedal, a pull to one side or a grinding noise. Our guide on Tyres and the MOT explains how tyres are tested, which works hand in hand with the brakes for safe stopping.

Spotting Brake Problems Before the Test

Brakes tend to warn you before they fail a test, so paying attention to how the car feels can save a failure. A brake pedal that feels soft or sinks slowly can point to a fluid or hose problem, while a squeal or grind often means the pads are worn.

A car that pulls to one side under braking suggests an imbalance. A warning light on the dashboard should never be ignored. If you notice any of these, it is worth having the brakes checked before your MOT rather than risking a fail. Catching a worn pad early is also cheaper than leaving it to damage the disc.

The Parking Brake in the Test

The parking brake, also called the handbrake, is tested as well as the foot brake. It is checked for how well it holds the car on the same rollers and needs to reach its own minimum figure to pass. A handbrake that has gone slack over time is a common reason for this part to fail, since the cable stretches with use.

This applies to electronic parking brakes too, which are now common on newer cars. They are tested for the same holding performance as a traditional lever, just operated by a switch. If your handbrake feels like it needs pulling higher than it used to or an electronic one has warned of a fault, it is worth having it adjusted before the test. Our guide on Top Reasons Cars Fail MOT covers the other big failure areas to watch.

Keep Your Brakes MOT Ready

This guide is part of our full MOT Guides hub, where the testing, cost and rules articles sit together so you can move to the exact detail you need next. When it is time to book, our team offers full MOT testing and repairs from our centre in Ely. You may also find it useful to read Top Reasons Cars Fail MOT, Tyres and the MOT and What an MOT Checks.

Common Questions