Wheel speed sensors are often called ABS sensors. You'll find them mounted on the axles of all ABS equipped vehicles on your wheel hubs, near the brake rotors. The ABS sensor is a vital part of the braking system. Without a working ABS wheel speed sensor, the ABS system will fail to work properly. Resulting in a ABS Light on your Dash and loss of your Antilock Brake System. Fit 2008 Mercedes-Benz GL320/11-12 Mercedes-Benz GL550 07-09 Mercedes-Benz ML320/06-10 Mercedes-Benz ML350/2010 Mercedes-Benz ML450/06-09 Mercedes-Benz ML500/08-10 Mercedes-Benz ML550/07-10 Mercedes-Benz ML63 AMG/07-09 Mercedes-Benz R320/06-12 Mercedes-Benz R350/06-08 Mercedes-Benz R500 /07 Mercedes-Benz R63 AMG