ABS Sensor Replacement for Purley Drivers

From Purley Cross it's about 15 minutes to our workshop in Hackbridge, up Foxley Lane and north on the A237. We read the ABS codes and test the circuit to find the real fault, and ABS sensor replacement starts from £89.

  • ★★★★★ 4.9/5 from 87 Google reviews
  • ~15 min from Purley
  • Mon–Sat 8am–8pm
Audi SQ5 in for brake and wheel-speed work at KITH Cars Garage & Bodyworks, Hackbridge

Flood-prone valleys, steep hills and ABS sensor corrosion

Purley sits in a valley, and the Caterham Bourne flooded parts of Purley and Kenley in early 2014, with flood alerts issued again since, including in 2024. Driving through standing water puts wheel hubs, sensors and their connectors under water, and although they're designed to cope with rain and spray, prolonged soaking and road grime speed up corrosion. The result is often an ABS light that comes on after wet weather, then clears, before eventually staying on. It's easy to ignore at first, but the system is switched off each time the light shows.

The hills are the other factor. Roads up to Russell Hill and around the valley are steep and winding, and on many cars the same wheel speed signals control hill-hold and the automatic functions of the electronic parking brake. When a sensor fails, those features often stop working along with ABS and stability control, which you'll soon notice pulling away uphill. Purley Cross and the A23 Brighton Road also bring heavy stop-start traffic, which wears brakes and means more frequent brake work, another common time for sensors to be disturbed.

We start with the ABS fault codes and live wheel speed data, then test the sensor circuit and inspect the ring or bearing encoder. Sensors that have been exposed to a lot of water are often seized in the hub, so we remove them carefully and clean the mounting before fitting the new one at the correct gap. If a connector has corroded, we repair it with a sealed connection. You'll have a written quote before we begin, and if the bearing is part of the problem, we'll explain why.

The route is up Foxley Lane (A2022) through Woodcote, then right onto the A237 and north through Wallington to Hackbridge, about 4.5 miles. With only the ABS light on, most cars are fine to drive carefully. Repairs are covered by our 3-month workmanship warranty.

ABS Sensor Replacement: what’s involved

Each wheel has a speed sensor that reads a toothed or magnetic ring turning with the hub or driveshaft. The ABS module constantly compares the four signals. If one wheel slows too quickly under braking, the system releases and reapplies that brake to stop it locking. The same signals feed traction control, stability control and often the speedometer, hill-hold and tyre pressure warning.

Older cars use passive sensors that generate their own signal. Most modern cars use active sensors, which are powered by the ABS module and often read a magnetic encoder built into the wheel bearing seal. Sensors sit right next to the brakes, exposed to heat, water, salt and brake dust, so corrosion, damaged wiring and failed connectors are common. When a signal drops out, the system switches ABS and stability control off and lights the warning. Your normal brakes still work.

From £89Written quote first
45 minutes–2 hoursTypical time in the workshop
3 monthsWorkmanship warranty
4.9★87 Google reviews

Signs of an ABS sensor fault

ABS warning light on

A steady ABS light means the system has switched itself off. Normal braking still works, but the wheels can lock under heavy braking.

Traction and stability lights too

Because they rely on the same wheel speed signals, the traction control or ESP light usually comes on with the ABS light.

Light comes and goes

An intermittent warning, often after bumps, in wet weather or at a certain speed, usually points to damaged wiring, a loose connector or a corroded sensor.

ABS pulsing at low speed

If the pedal pulses and the ABS activates when stopping gently, a sensor may be giving a false reading from a dirty sensor or a cracked reluctor ring.

Speedometer or tyre warning faults

On cars that take road speed or tyre pressure monitoring from the wheel sensors, a faulty sensor can upset the speedometer or set a tyre warning.

Other systems disabled

Hill-hold, cruise control, stop-start and some electric parking brake functions may stop working when a wheel speed signal is missing.

When should it be done?

ABS sensors have no replacement interval. They are replaced when they fail or when their wiring is damaged. Get the car checked as soon as the ABS light comes on, because the car won't stop as well in an emergency on a wet road without ABS and stability control. An ABS warning light that stays on is also an MOT failure. Faults often show up after brake, hub or suspension work, when a sensor or its wiring may have been disturbed.

  • ABS, traction or stability warning light on
  • Intermittent warnings in wet weather or over bumps
  • Warning lights after brake, wheel bearing or suspension work
  • Before an MOT if the ABS light is showing

How we replace an ABS sensor

  1. Check-in and symptomsWe ask when the light appears and whether any work has been done recently, as disturbed wiring after brake or suspension work is common.
  2. Diagnostic scanWe read the ABS module fault codes to identify which wheel is affected and whether the fault is signal, circuit or plausibility related.
  3. Live data and testingWe compare live wheel speed readings on a road test or ramp and test the sensor circuit with a multimeter or oscilloscope to separate sensor, wiring and ring faults.
  4. Inspect the ring and bearingWe check the reluctor ring or magnetic encoder for cracks, corrosion or damage and check the wheel bearing for play, as either can cause a false signal.
  5. Written quoteWe explain the cause and give you a written quote. If the encoder is built into the wheel bearing, we'll explain why the bearing may need replacing.
  6. Replace the sensorWe carefully remove the old sensor, which is often seized in the hub, clean the mounting, and fit the new sensor with its wiring routed and secured correctly.
  7. Clear codes and road testWe clear the fault codes, road test to confirm all four wheel speeds read correctly and the warning lights stay off, and run any calibration the car needs.

Parts we fit

Sensors must match the car exactly. Active and passive types are not interchangeable, and connectors and lengths vary between models and even between axles. We fit OE or OE-equivalent sensors from manufacturers such as Bosch, ATE or Continental. Where the wiring is damaged we repair it properly with sealed connectors, and where the fault is in a reluctor ring or a wheel bearing encoder, we replace that part rather than just the sensor.

  • OE or OE-equivalent ABS wheel speed sensors
  • Reluctor rings where cracked or corroded
  • Wheel bearings with integral magnetic encoders where required
  • Sensor wiring and sealed connector repairs

How long it takes

45 minutes–2 hours

A straightforward sensor swap often takes under an hour. Seized sensors, wiring repairs or a reluctor ring or wheel bearing replacement take longer. Most jobs are completed the same day.

What’s included

  • ABS system fault code scan
  • Wheel speed live data check
  • Sensor circuit and reluctor ring inspection
  • Correct replacement sensor fitted
  • Fault codes cleared
  • Road test to confirm the warning lights stay off

From Purley to our Hackbridge workshop

From Purley Cross head west up Foxley Lane (A2022) through Woodcote to the mini-roundabout with Woodcote Road and Smitham Bottom Lane (A237). Turn right onto Woodcote Road (A237) and follow the A237 north through Wallington as it becomes Manor Road and then London Road into Hackbridge; Soho Mills is on the right.

Take Foxley Lane up through Woodcote, then the A237 north to Hackbridge, about 15 minutes. With just the ABS light on, drive gently and allow more stopping distance downhill.

Directions from Purley

About Purley

Purley is a green, hilly suburb on the edge of the North Downs about three miles south of Croydon, which grew rapidly in the 1920s and 1930s as a place of spacious homes. Its small town centre sits in a valley around Purley Cross, where the A23, A22, A235 and A2022 all meet, while the surrounding roads climb up to detached and semi-detached houses in Woodcote, Russell Hill, Riddlesdown and the private Webb Estate. It feels quieter and more affluent than central Croydon, but the Purley Cross gyratory is a well-known bottleneck and many side roads are steep and winding.

Places nearby: Purley Cross, Purley station, Purley War Memorial Hospital, Webb Estate, Promenade de Verdun, Russell Hill school buildings

Postcodes: CR8 · London Borough of Croydon

More about KITH for Purley drivers

ABS Sensor Replacement in Purley: your questions answered

Can driving through floodwater cause an ABS fault?

It can. Sensors and connectors sit low down by the hubs, and prolonged exposure to water and grime can corrode them or get into damaged wiring. It may not show up straight away, so if the light appears in the weeks after, mention it when you book.

Why has my hill-hold stopped working at the same time as the ABS light?

Hill-hold and some electronic parking brake functions rely on wheel speed signals. When a sensor fails, the car switches them off along with ABS and stability control. Fixing the sensor usually restores them.

Is a seized ABS sensor expensive to remove?

It can take longer, and occasionally the sensor breaks and needs drilling out. We'll tell you if yours looks badly seized before we start, and include it in your written quote.

Is it safe to drive with the ABS light on?

The car will still brake normally, so you can usually drive it carefully to the garage. But without ABS and stability control the wheels can lock under hard braking, so leave extra distance. If the brake warning light is on as well, get advice before driving.

Will an ABS light fail the MOT?

Yes. An ABS warning light that stays on, or doesn't come on when the ignition is switched on, is an MOT failure. The same applies to the electronic stability control warning on cars that have it.

Can I just clear the code?

If the fault is still there, the ABS module will find it again, usually within a short drive. Clearing codes without finding the cause just delays the repair.

Why might I need a wheel bearing as well?

On many modern cars the magnetic ring that the sensor reads is built into the wheel bearing seal. If that encoder is damaged or the bearing has excessive play, a new sensor won't cure the fault, and the bearing has to be replaced.

Why did the light come on after my brakes were done?

ABS sensors and their wiring sit close to the brakes and hubs, so they can be knocked, stretched or left unplugged during brake or suspension work. Sometimes an old sensor that was already corroded fails when disturbed. A quick scan shows which wheel is affected.

Price your ABS sensor replacement now

Enter your reg and we’ll look up your car and price the job from our own labour rates and the book time for your model. Then book it in with a fixed written quote before any work starts.

  • Free, about 30 seconds, no sign-up
  • Parts, labour and VAT included
  • 3-month workmanship warranty
  • Collection from Purley can be arranged
“It’s rare to find a garage you can truly trust. Fair price, brilliant customer service.”Thinushan K. · ★★★★★ Google

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