I always replace the sensors.

If the pads have not worn to the sensor and no part of the senor has worn or contacted the rotor, then you could probably reuse it if you can pull it out of the pad without damaging it.

But for $2, I always just figure there's no harm in getting a new one.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record