Brakes are the single biggest cause of MOT failures I see come through the door, and they're also the category where the wording confuses people most. A certificate can say your braking is 'imbalanced', that a disc is 'significantly worn' or that efficiency is 'below requirement', and none of that tells you which part is at fault.
Brakes are the single biggest cause of MOT failures I see come through the door, and they're also the category where the wording confuses people most. A certificate can say your braking is 'imbalanced', that a disc is 'significantly worn' or that efficiency is 'below requirement', and none of that tells you which part is at fault.
The MOT brake test is partly visual and partly measured on a roller brake tester. That matters, because a measured failure (efficiency or imbalance) is a number, not a diagnosis. It tells the tester the car isn't stopping properly; it doesn't tell anybody whether that's a sticking caliper, a contaminated pad, a collapsed flexi hose or a worn-out rear shoe.
Below are the brake failures and advisories that turn up most often, what each one normally means, and what I'd physically check before ordering a single part.
Brake pad(s) less than 1.5mm thick
The friction material left on at least one brake pad has been measured or judged below 1.5mm. That's the point where there isn't enough material left to guarantee the pad will still be doing its job before your next service, and it's also the point where the backing plate starts getting close to the disc.
Full explanation of Brake pad(s) less than 1.5mm thick
Brake disc significantly and obviously worn
The disc has lost enough thickness, or picked up enough scoring and pitting, that the tester judged it no longer fit for purpose. A pronounced lip around the outer edge is usually what triggers this — that lip is the original thickness, and everything inside it is what's worn away.
Full explanation of Brake disc significantly and obviously worn
Braking effort imbalanced across an axle
On the roller brake tester, one wheel on that axle produced noticeably less braking force than the other. It's a measurement, not a diagnosis — it says the two sides aren't matching, but it doesn't say why. In real driving this is what makes a car pull to one side under braking.
Full explanation of Braking effort imbalanced across an axle
Parking brake efficiency below requirement
The handbrake didn't generate enough braking force on the tester to meet the minimum required for the vehicle. Note that this is a measured result — a handbrake that feels fine on a flat driveway can still be well under the limit.
Full explanation of Parking brake efficiency below requirement
Brake fluid contaminated
The fluid in the reservoir was judged to be contaminated — usually dark, cloudy or visibly full of debris. Brake fluid absorbs moisture from the air over time, and moisture lowers its boiling point, which is what causes a long pedal after heavy braking.
Full explanation of Brake fluid contaminated
Brake pipe excessively corroded
A rigid brake pipe has corroded to the point where the tester judged its strength compromised. There's a real difference between surface rust, which is normal on an older car, and flaking corrosion that's eating into the wall of the pipe — this wording means the latter.
Full explanation of Brake pipe excessively corroded
Brake hose damaged, chafed or corroded
The flexible rubber hose that carries fluid from the hard pipe on the body to the moving caliper has been marked down. The tester bends and inspects each hose with the wheels on full lock, so faults that only show at an angle get found. Surface cracking is usually Minor; exposed reinforcement, a bulge under pressure or a badly corroded end fitting is Major or Dangerous.
Full explanation of Brake hose damaged, chafed or corroded
Brake binding
One brake isn't fully releasing, so it's rubbing all the time the car is moving. On the roller brake tester it shows as drag on a wheel that should be spinning free. Left alone it destroys pads and discs, eats fuel, and can get hot enough to boil the fluid at that corner.
Full explanation of Brake binding
How brakes defects are graded
Every MOT defect is recorded as dangerous, major or minor. Dangerous and major both fail the test; the difference is that a dangerous defect means the car is not roadworthy and must not be driven away. A minor defect passes but is recorded on the certificate, and an advisory is a note that something is wearing and will need attention before the next test. Tester notes in the brakes section use standard DVSA wording, which is why the phrasing on your certificate looks nothing like plain English — the pages above translate it.
Getting a brakes failure put right
You are free to take the car anywhere for the repair — there is no obligation to have the testing station do the work, and getting a second opinion on a big quote is sensible. Ask for the failed item to be shown to you on the ramp; a genuine defect is always something a mechanic can point at. Once repaired, a partial retest within ten working days covers the listed items without paying a second full test fee.
Avoiding it next year
Most brakes failures are found on a pre-MOT check for a fraction of the cost of a failure plus retest, because they are inspected before the clock is running. An MOT at Bob's Mechanical Repairs in Birnam, Dunkeld is £54.85, and anything found is explained and priced before work is agreed. Bob has 32 years on the tools, so the advice you get is what he would do with his own car.
Common questions
Can I drive away after a brakes MOT failure? Only if the old certificate is still valid and the defect is not dangerous. A defect recorded as dangerous means the car must not be driven on the road until it is repaired, and driving it can mean a fine and points.
Do I pay again for the retest? If the car is left at the testing station and the repair is done there, the partial retest is usually free. If you take it away and bring it back within ten working days, a partial retest is free for the listed items; after that a full test fee applies.
What does an advisory in this section mean? An advisory is a pass with a warning: the item is not bad enough to fail today but is wearing. Advisories on the same item two years running are the ones worth acting on before they become failures.
Decode your exact MOT wording or browse all MOT failure categories.