ABS rings are an essential part in all modern braking systems, and faulty rings will result in an instant MOT failure. ABS rings fit on each wheel, working with sensors to send wheel-speed data to the Anti-lock Braking System controller. Using this data, the ABS controller stops the wheels from locking up by ensuring each one stays in sync. It does this by applying hydraulic pressure at just the right time. A faulty ABS ring will cause a warning signal to light up on your dashboard. When this happens you must replace the faulty ring immediately. Without vital data from the ABS rings and their sensors, the controller won’t do its job properly and your car will become unsafe to drive.