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 06 Mercedes-Benz CLS500/06 Mercedes-Benz CLS55 AMG /07-10 Mercedes-Benz CLS550 /07-10 Mercedes-Benz CLS63 AMG /03-09 Mercedes-Benz E320 /06-09 Mercedes-Benz E350 /03-04 Mercedes-Benz E500/03-06 Mercedes-Benz E55 AMG/07-09 Mercedes-Benz E550 /07-09 Mercedes-Benz E63 AMG/09 Mercedes-Benz Sl63 AMG