Wheel speed sensors are among the most numerous sensors on modern vehicles, with at least four fitted to every car. These sensors provide critical data to ABS, traction control, stability control, and transmission systems, making them essential for vehicle safety and drivability. ## How Wheel Speed Sensors Work Wheel speed sensors use magnetic principles to detect wheel rotation. A toothed reluctor ring, or tone wheel, is mounted on the wheel hub or CV joint. As the wheel rotates, the teeth pass by a magnetic sensor that generates a voltage pulse for each tooth. The sensor output is a square wave signal whose frequency corresponds to wheel speed. Faster wheel rotation produces a higher frequency signal. The ABS control module counts these pulses to determine the speed of each wheel. The number of teeth on the reluctor ring determines the resolution of the speed measurement. More teeth provide finer speed resolution, improving the ABS and traction control system's ability to detect wheel slip. Active sensors use Hall effect technology to produce a digital signal regardless of speed. Passive sensors generate AC voltage from magnetic induction and may not function reliably at very low speeds. ## Wheel Speed Sensors and Safety Systems ABS depends entirely on wheel speed sensors. When one wheel decelerates faster than the others, the ABS recognises it is about to lock and releases brake pressure to that wheel. Without speed sensors, ABS cannot operate. Traction control uses wheel speed sensors to detect wheelspin. When one wheel loses grip and spins faster than the others, traction control can apply braking or reduce engine power to restore grip. This requires accurate speed information from all wheels. Electronic stability programme uses wheel speed data alongside steering angle and yaw rate sensors to detect loss of control. If the car is sliding sideways, stability control can selectively brake wheels to restore the intended driving line. Automatic transmissions use wheel speed data to determine when to shift gears. The transmission adjusts shift points based on vehicle speed, ensuring the engine remains in the optimal RPM range for efficiency or performance. ## Signs of Wheel Speed Sensor Problems An illuminated ABS warning light indicates a problem with the wheel speed sensor system. The specific wheel affected may be identified by diagnostic equipment. Common causes include damaged sensor wiring, corroded connectors, and failed sensor elements. Incorrect speedometer reading or automatic transmission shifting problems can indicate a wheel speed sensor fault. The speedometer may display an incorrect speed if all sensors are providing inaccurate data. If multiple sensors fail simultaneously, the car may disable ABS and stability control entirely. The brake system remains functional but without anti-lock protection. This represents a significant safety reduction. ## Frequently Asked Questions **How much does wheel speed sensor replacement cost?** Wheel speed sensors cost £20-60 each for parts, with labour adding £30-100 depending on accessibility. Rear sensors on some vehicles are very easy to replace, while front sensors on all-wheel-drive vehicles may require significant disassembly. **Can I clean a wheel speed sensor?** The sensor itself is sealed and cannot be cleaned. However, the sensor tip can accumulate metal debris from the reluctor ring. Cleaning the sensor mounting area and removing accumulated metal filings with compressed air can restore function if the sensor is not physically damaged. **Do wheel speed sensors affect tyre pressure monitoring?** Tyre pressure monitoring systems use either direct pressure sensors in the valve stem or indirect calculations from wheel speed sensors. The two systems are separate, but a failed wheel speed sensor can prevent indirect TPMS from functioning.

Official Resources: GOV.UK Check Vehicle Tax | GOV.UK Vehicle Tax | DVLA Online | MOT Check

Frequently Asked Questions

Q: How much is car tax (VED) in the UK 2026?
Car tax rates in the UK depend on your vehicle's CO2 emissions and list price. Standard rates start from £190 per year for petrol and diesel cars, with zero-rated VED for EVs. First-year rates vary from £0 to £2,605 depending on emissions. Additional premiums apply for vehicles over £40,000.

Q: How do I check if my car is taxed online?
You can check your vehicle's tax status for free on the Gov.uk website at gov.uk/check-vehicle-tax. You'll need your vehicle's registration number (number plate). You can also check via the Motor Insurance Database to verify road tax and insurance status simultaneously.

Q: Can I get a refund on car tax if I sell my vehicle?
Yes — if you sell or scrap your vehicle, you can claim a refund on any full months of remaining road tax. Contact DVLA with the V11 reminder letter or apply online at gov.uk. Refunds are usually processed within 4-6 weeks.

Q: Is road tax refund available when transferring ownership?
No — road tax does not transfer with the vehicle. When you sell your car, the tax is automatically cancelled and any remaining months are refunded to you by DVLA. The new owner must tax the vehicle immediately. As a buyer, always verify the vehicle's tax status before purchasing. Related: UK Car Steering Angle Sensor Guide 2026 | UK Car Yaw Rate Sensor Guide 2026 | UK Car Parking Sensors Guide 2026 | Car Tax and MOT Connection UK 2026.

Q: What is the luxury car tax threshold in the UK 2026?
The additional rate for vehicles over £40,000 (list price) adds £410 per year to standard VED rates for years 2-6 of registration. This surcharge brings the annual cost for high-emission vehicles over £40,000 to around £600-690 per year. Pure EVs under £40,000 pay zero VED.