What is an ABS Sensor?
The little sensor at each wheel that stops your brakes from locking up.
Simplified animation — not to scale.
In plain English
An ABS (Anti-lock Braking System) sensor sits at each wheel and constantly reports how fast that wheel is spinning. The ABS module uses those four readings to detect a wheel locking up under braking and rapidly releases the brake on that wheel to keep it rolling — so you can still steer in an emergency stop.
"Like fingers tapping the brakes for you, far faster than any human could — keeping the wheels rolling so you can steer."
How it works
A small magnetic sensor reads a toothed ring on the wheel hub. If one wheel suddenly slows much faster than the others, the ABS module pulses the brake on that wheel dozens of times per second until grip returns. It also feeds wheel-speed data to traction control, stability control and hill-start assist.
Signs of trouble
- ⚠ABS warning light on the dashboard
- ⚠Traction control or stability light staying on
- ⚠Speedometer behaves erratically
- ⚠Brakes feel normal but ABS won't engage in an emergency stop
- ⚠Brake pedal pulses at low speed for no reason
£70–£200 fitted per wheel
Always get a written quote. Prices vary by car, region, and parts brand.