One sensor required per wheel. Right and Left Sensors are the same, Front and Rear sensors are different.
2002-2006 R50 MINI Cooper and R53 Cooper S Hatchback
2005-2008 R52 MINI Cooper and Cooper S Convertibles
For the Rear sensor, see NMS7621.
These sensors play a vital part of the ABS system, flat tire monitor, cruise control, and the DSC (or ASC). If you have these error lights on, then it's a good chance you need one of these sensors replaced.
Make note of the proper routing of the sensor wires before removing and match when installing. Clean the speed sensor mounting bolts and holes, and use anti-seize compound on the bolts. Torque mounting bolts to 6 ft-lbs (for both fronts and rears).