Is it necessary to change the sensor every time you change the pads i need help because I'm about to buy the front power kit brake pads

 

You need to remove either the inner or the outer side to get the pads out anyway & the issue I have experienced is that the composite material that the makes up the sensor gets brittle from the heat and is very difficult to remove & reinstall without it cracking, making reinstalling it impossible. They are not too expensive though.

 

It's smart to do while you're in there as they are cheap.