Part explained
ABS wheel-speed sensor: replacement, symptoms, MOT
An ABS sensor is a small electromagnetic pickup mounted at each wheel. If one fails, the ABS system disables itself (amber warning light), ESC/ASR usually drop out with it and even the speedometer can glitch. This page explains how to identify the failed sensor, what replacement costs and why this is an instant MOT (APK) failure.
By the onderdelen.autos editorial team · Updated · About the editorial team
What does the ABS sensor do?
Each wheel hub has a toothed reluctor ring and a sensor that reads the teeth as the wheel rotates. The ABS controller uses those signals to compare individual wheel speeds — when one wheel decelerates faster than the others, the ABS modulates brake pressure. The same signals feed ESC (stability control), ASR (traction control), the tyre-pressure system (indirect TPMS) and on many cars the speedometer. So a single failed sensor can light up a whole cascade of warning lamps.
Signs of a failed ABS sensor
- ABS warning light on (steady amber) on the dashboard.
- ESC or ASR light on alongside — these usually disable when ABS drops out.
- Speedometer jumps or freezes, especially at low speed (< 20 km/h).
- Fault code C0035 to C0040 ("wheel speed sensor circuit") on an OBD-II or ABS scanner.
- ABS activates at strange moments — pulsing brake pedal without hard braking.
- Cruise control refuses to engage or drops out unexpectedly.
- Indirect TPMS keeps asking to be reset.
When to replace
No fixed interval — replace on complaint. An ABS sensor fails through connector corrosion, a broken cable (often where it runs past a control arm and flexes with every suspension movement) or a dirty sensor seat where metal swarf sticks to the magnet. Pinpoint with an ABS scanner: the code identifies the wheel (LF / RF / LR / RR). When in doubt: measure the sensor resistance (typically 1 – 2 kΩ) or scope the signal during slow wheel rotation. **MOT-critical**: a lit ABS lamp is an instant failure at the annual MOT (APK) — get it resolved before driving to the test.
What does a new ABS sensor cost?
Aftermarket: € 25 – € 60 each. OEM quality: € 50 – € 100. Used from a Dutch dismantler: € 10 – € 40, but inspect the connector and cable for corrosion or breaks — that's the part that usually fails, not the sensor itself. Workshop cost: 0.5 – 1 hour labour per sensor. Sometimes the issue isn't even replacement but a dirty seat — cleaning costs nothing and is always step one.
| Condition | From | To |
|---|---|---|
| New | € 25 | € 100 |
| Used / refurbished | € 10 | € 40 |
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DIY or workshop?
Difficulty: Medium
On most cars this is a one-hour job per wheel: wheel off, sensor bolt out (often seized by corrosion — penetrating fluid, not brute force), old sensor out, clean the seat, new sensor in, reconnect and wheel back on. Don't forget to clear the code after replacement — the ABS controller stores the fault and keeps the lamp on until you actively clear it. Pull the sensor straight out; levering can damage the reluctor ring and that's a far more expensive fix.
- Jack and axle stands (wheel has to come off)
- Socket set including Torx for the sensor bolt (often T20 or T25)
- Wire brush or sandpaper to clean the sensor seat
- OBD-II or ABS scanner to read the code and clear it after replacement
Frequently asked questions
Which ABS sensor is failed — how do I find out?
With an OBD-II or ABS scanner. The fault code identifies the wheel (often C0035 = left front, C0036 = right front, etc. — exact mapping per brand). Without a scanner you can guess, but the sensor costs enough that a diagnostic session at a workshop (€ 30 – € 50) pays itself back.
Is it dangerous to drive with the ABS light on?
Not acutely while driving calmly, but in an emergency brake you have no ABS. ESC and ASR usually disable too — on a wet road or a slippery bend that's a serious risk. Plus: instant MOT failure. Don't put it off.
Can a dirty sensor seat cause the same symptoms?
Yes — and often. Before buying a new sensor: pull the old one, clean the seat with a wire brush or sandpaper (metal swarf disrupts the magnetic field), refit and clear the code. In about a third of cases the complaint is resolved that way.
Can I buy a used ABS sensor?
Yes, ABS sensors are often interchangeable within a single model and year. Check the connector type and cable shape carefully. Used is € 10 – € 40 — a fine option for an older car.
Do I need to code anything after replacement?
On most ABS systems no — the controller recognises the working sensor as soon as you clear the code and drive a few metres. On some premium brands a calibration drive is needed that the workshop performs on the tester.
Related parts
ABS sensors in Dutch stock
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