What Causes a Car ABS Sensor to Fail?
2 Answers
There are two main reasons for the failure of a car ABS sensor: the ABS sensor being covered and loose connections in the system wiring. ABS Sensor Being Covered: When the sensing part of the ABS speed sensor is covered by dirt, mud, or other contaminants, it affects the sensor's ability to detect the corresponding speed signal. As a result, the ABS control unit cannot determine the vehicle speed or calculate the wheel slip ratio, preventing it from issuing appropriate commands to adjust braking. Cleaning the contaminants from the speed sensor and adjusting the gap between the sensor and the signal ring can restore normal function. Loose Connections in System Wiring: Poor signal quality caused by loose connections in the system wiring or poor contact in the ABS relay can lead to system failure. The most common issue is a loose speed sensor connector, which causes the fault. In such cases, the ABS control unit's fault memory will also indicate poor speed sensor signal quality. Check the wiring connections and reconnect any loose parts.
I've encountered numerous cases of ABS sensor failures, mostly caused by physical damage and environmental factors. The sensors are installed near the wheels and are prone to direct damage from road debris like flying stones. Accumulated dirt and dust in the wheel hub area can block the sensors, leading to signal interruption. In winter, road salt with strong corrosive properties accelerates sensor rusting and aging. Electrical circuit issues are also common, such as aged wiring, loose connections, or short circuits that disrupt wheel speed data transmission. Careless handling of wiring during repairs can also cause problems. ABS sensors interact with magnetic rings and wheel speed rings to detect velocity. When faulty, the ABS warning light activates, and the braking system may fail, causing dangerous wheel lock-up during braking. It's recommended to stop immediately for inspection or visit a professional repair shop when this occurs to avoid accidents on slippery roads.
