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ABS Sensor Replacement
Typical Cost: Low
Mobile Repair? Yes
Typical Lead Time: 24 - 48 hours depending on part availability
What does an ABS wheel speed sensor do?
The ABS, or anti-lock braking system, on your car is a super important system that prevents your wheels from locking up and therefore simply skidding across the road surface. The ABS wheel speed sensor tells the ABS ECU how fast each wheel is turning (or not!) so that the system can determine whether a wheel has locked up or is moving slower than the other wheel on the axle.
How does an ABS wheel speed sensor work and what are the components?
Wheel speed sensors are, in essence, a simple magnet which is encased in a coil of wire that is held static somewhere on the hub carrier of the wheel. On the rotating part of the wheel is a toothed ring (called a reluctor ring). As the raised part of the toothed ring comes into proximity of the magnet it creates an electrical field this brief pulse of current gets sent to the ABS control unit. As there are many teeth on the reluctor ring, there are many pulses that get sent to the ABS control unit, with every revolution of the wheel and obviously the faster the wheel turns, the higher the number of pulses per second are sent.
When the ABS control unit receives this information, it instantly compares it to the other wheel on the axle (or even all four wheels) and if there is a difference of a predetermined % between the two and it is under another predetermined number of pulses per second, under braking, it will quickly release and reapply the brake pressure valve to allow the wheel to rotate again, rather than lock up.
So basically, if a wheel is locked up, it knows and releases the brake to allow it to turn again briefly before quickly re-applying the brake.
All this happens extremely quickly and you will feel vibration through the brake pedal and may even hear it too.
Typical symptoms that require an ABS sensor to be replaced.
- The car's ABS warning light stays on permanently once the engine is started.
- The brakes lock up very easily when braking on slippery surfaces.
- The brakes do not respond as well as normal under hard braking
What happens during an ABS sensor replacement?
Changing an ABS sensor is a routine repair for all mechanics and can be done both kerbside as well as in the workshop, providing it is safe to do so.
Whilst there are variations between manufacturers, the basics are pretty similar.
The mechanic will;
- Diagnostically inspect the ABS system.
- If necessary, replace the faulty ABS sensor and re-test the component.
- If the ABS module is at fault, advise on the best course of action in order to have it repaired.
- Test drive and inspect the braking system.
What does this repair cover?
Unless otherwise stated, the quote for your ABS sensor to be replaced will cover;
- The cost of the ABS sensor and diagnostic
- Coming to you
- Fitting of the parts
- Disposal of the old parts (unless you request to keep them)
- VAT (if applicable)
- 12 months parts and labour warranty
What to search for on the ClickMechanic site?
ABS wheel speed sensor replacement - front (one)
ABS wheel speed sensor replacement - rear (one)
Associated repairs
ABS Warning Light Inspection
How much does it cost to have an ABS sensor replaced?
The cost of an ABS sensor replacement depends on your car and what parts your car's manufacturer recommends.
Find out what you could save by visiting ClickMechanic
https://www.clickmechanic.com/bookings/car
FAQ’s
Can I supply my own parts?
No, we will not fit customer supplied parts unless they are a brand new item, purchased from a dealership with the receipt as proof of purchase. There is no flexibility over this due to insurance and warranty issues.
What happens if the mechanic finds that the ABS sensor doesn’t require changing and the problem is due to another issue?
In this scenario, the mechanic will provide a no obligation quote for the correct repair. Should you accept this, the mechanic can alter the booking accordingly. If you decide not to go ahead with the alternative repair, the mechanic can change the booking to a call out and diagnostic booking and charge according to the time spent with the vehicle and call out.