2002 Mercedes Benz S430

Brakes problem
2002 Mercedes Benz S430 V8 Two Wheel Drive Automatic 80000 miles

My breaks were replace (Front and back) as were rotors, they forgot to put new sensors in. Sensor indicator comes on as you start car. My question is how to replace the sensors. Can it be done without taking off the new breaks and rotors? I know cost is about $7 per sensor and I am not sure how many. Having problem getting them to replace with out additional cost. I ofter change breaks etc so I can do some repair myself. Where are the sensor loacated and how difficut to replace. Thanks for any advice.

February 25, 2010.

The brake pad contact sensors are installed on each wheel's brake caliper and are fairly simple to replace.

Feb 25, 2010.