brakes

Hi, I have a F20 120i 2017. The rear pads are almost finished but have not yet activated teh sensor. I am struggling to find stock of the sensor. Can I replace the brake pads and leave the sensor intact or must the sensor be replaced even though it has not activated?

So my rear brakes locked up and I had to have the car towed twice. Once to my house and then from brakes shop to a very reputable workshop in Tygervalley (Cape Town). Breaks was serviced and bleeded, but still locks. Next in line is ABS unit, but there is very little experience, as I am made to...