MOT defect file
Braking efficiency below requirement
Last updated
Quick answer
The vehicle did not achieve the required braking force on test. This is a failure item and needs diagnosis before further use.
- Typical cost
- £120–£450
- DIY viability
- Garage job
What you might notice
- The car pulling to one side under braking, which is the classic sign of uneven effort across an axle
- A longer stop than you expect, particularly from motorway speeds
- A handbrake that needs several more clicks than it used to, or will not hold on a hill
- Often nothing detectable from the driver's seat — the rolling road measures forces at each wheel that you cannot feel on the road
What causes it
- A seized or partially seized calliper or wheel cylinder, so one wheel contributes little or nothing to the total
- Rear drum brakes with glazed shoes, seized adjusters or a stretched handbrake cable
- Friction surfaces contaminated by a leaking calliper seal, wheel cylinder or hub seal
- Old brake fluid that has absorbed moisture, or a failing servo or split vacuum hose reducing pedal assistance
Advisory or failure?
This is a failure item with no advisory version. A car must record a service brake efficiency of at least 50% and a parking brake efficiency of at least 16%, and falling short of either is a major defect. It is also a major defect if the effort at one wheel is less than 70% of the effort at its partner on the same axle — an imbalance of more than 30% — even where the overall efficiency figure passes. Grading escalates to dangerous where the service brake achieves less than half the efficiency required, or where a steered axle is grossly imbalanced, because the car will pull hard to one side in an emergency stop.
Can you fix it yourself?
Garage job
Diagnosis needs a rolling road or a decelerometer to know which wheel is short and by how much; guessing from the driver's seat usually means replacing parts that were fine. The individual repairs behind the failure — pads, a cable, a calliper — are within reach of a competent home mechanic, but you cannot confirm the fix without a brake test, and the retest measures exactly the same numbers on the same machine.
What it costs
The band runs from a rear brake adjustment and a new handbrake cable at £120 to £180, through a calliper with pads and a disc at £250 to £350 per corner, up to hydraulic work and a full fluid change at the top. What pushes it up is a fault present at more than one corner, a seized bleed nipple that forces a whole calliper to be replaced rather than serviced, and rear electronic parking brakes, where the motorised calliper alone costs more than a conventional one. Budget £50 to £80 of diagnostic time before any parts are ordered.
What happens if you ignore it
A car that fails the brake test is, by definition, not stopping as well as the law requires, and the shortfall reveals itself in precisely the emergency you were hoping to avoid. Using the vehicle after the certificate expires is an offence on its own, and using one in a dangerous condition brings a fine and three penalty points, with an insurer entitled to take a dim view of a known defect after a claim. Mechanically, a seized calliper left dragging also destroys the pad and disc it is rubbing on, so a modest repair becomes a larger one within a few hundred miles.
This is general guidance, not a diagnosis. The severity DVSA records depends on the specific fault found, so the same item can appear as an advisory on one test and a failure on another. Ask a qualified tester or mechanic to inspect the vehicle.
Has this been recorded on your car?
Check the full MOT history for any UK registration.