The parking brake gets applied several thousand times a year and inspected essentially never. It is also the only braking system whose failure happens while nobody is behind the wheel.
| Component | Complaints | Involved a crash | Crash rate |
|---|---|---|---|
| Parking brake | 2,886 | 394 | 13.7% |
| Service brakes | 29,685 | 2,197 | 7.4% |
| Steering | 62,369 | 2,308 | 3.7% |
| Suspension | 29,812 | 1,014 | 3.4% |
Ten times fewer complaints than the service brakes, and nearly double the crash rate.
The reason is who is present
Every other failure on that table happens to a driver. Brakes fade and the driver pumps them, downshifts, aims for the verge. Steering goes heavy and the driver still has some control. There is a person in the loop with options.
A parking brake fails after the driver has walked away. The car rolls, and the only thing deciding what happens next is the gradient and what is downhill.
It also fails in the places with the most pedestrians: car parks, driveways, kerbside spaces on hills. The 123 injuries recorded across these complaints include people who were not in any vehicle at all.
How it fails, and the warning you get
Cable systems stretch. It happens over years, and the car holds on progressively less slope — fine on the flat, creeping on a mild incline, sliding on anything steep. That is a genuine warning, and it is ignored because the failure is gradual enough to look like normal ageing.
Drum-in-hat mechanisms seize instead. The shoes rust to the drum and stop moving, so the lever travels further and further while doing less. This is common on cars that spend their lives in the flat and are parked in gear.
Electronic parking brakes remove the cable and with it the warning. They engage or they log a fault. The gradual degradation that told you something was wrong is replaced by binary behaviour, which is better until the day it is not.
Why it goes untested
Most drivers park on the flat most of the time, and on the flat the transmission does the work. A car in park with a failed parking brake behaves identically to one with a working parking brake.
So the system can be entirely dead for years without anybody discovering it — until the one occasion when the car is left on a slope and the transmission pawl is asked to hold the whole vehicle by itself.
That pawl is a small piece of hardened steel. It is designed as a supplement to the parking brake, not a replacement for it.
The one-minute test
Find a slope with something noticeable to it. Apply the parking brake, select neutral, and release the footbrake slowly.
The car should hold still. Any creep means the system is not doing its job, and that is worth acting on before the next time you park somewhere with a gradient.
Twice a year is enough. It is the only check that actually loads the system, and it costs a minute in a supermarket car park.
On a used car it is worth doing during the viewing, alongside checking whether any recalls are outstanding — a free VIN check covers the second part.
Frequently asked questions
How often do parking brakes fail?
2,886 complaints name the parking brake specifically, which is modest volume — but 394 of them involved a crash, a rate of 13.7%. Service brake complaints run at 7.4%, so a parking brake fault is roughly twice as likely to end in a collision.
Why is a rollaway so dangerous?
Because nobody is in the car. Every other brake failure happens with a driver present who can steer, downshift or aim for something soft. A vehicle that rolls away from a parking space does so unattended, usually in a car park or a driveway where people walk.
Do electronic parking brakes fail differently?
They shift the failure from mechanical to electrical. A cable brake fails gradually — it stretches, holds on less slope each month, and gives warning. An electronic one either engages or reports a fault, so the degradation warning that cable systems provide is largely absent.
How do I test my parking brake?
Find a noticeable slope, apply the parking brake, select neutral and gently release the footbrake. The car should hold without creeping. Doing this on a slight incline twice a year takes a minute and is the only routine check that actually loads the system.
Denis Kataev is a serial solopreneur and the founder of ForCar. With 15+ years in software engineering and 10 years in SEO, he builds data-driven products end to end — backed by a sharp eye for design. At ForCar he mines proprietary vehicle datasets, turning raw numbers into buying advice you can actually trust.
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