never worked on a 300, but speaking from experience.
there is probably a bunch of dirt, maybe rust, between the sensor and the knuckle holding it in.
if you are just R&I it. spray it down with penetrant. take a flat punch or chisel and lightly tap on the bolt bracket. this should help break it loose. maybe even take off the rotor to gain clearance to hammer on it from the other side.
if you are replacing it hit it harder.
on some repairs I have had to use a air hammer to remove the ASB sensor.
Last edited by Mr T2U; 04/18/15 11:20 AM.