I was swapping out my front speed sensor and a piece of it broke off and fell into the hub. I can see it in there but can't get it out without pulling the hub off and I currently don't have a socket big enough to pull it off. I tried installing the new sensor and I'm still getting a DTC for that sensor. Will that piece floating around in the hub mess up the new one? Second question is how does the speed sensor work? As I was turning the hub, I didn't see anything for the sensor to read as the hub turned.

 

The sensor sticks into the hub next to the slotted tone ring. The ring may not be visible through the sensor hole.
Having the piece of the old sensor in there isn't good for the ball bearings. The piece could jam against the new one, I suppose.
A code for the sensor doesn't necessarily mean it's bad. Did you do any electrical troubleshooting before you decided to replace the sensor?

 

No, I didn't test it. I saw where the wire cover had been sliced and I could see the metal strands of the wire inside. Assumed it was enough of a break to trigger the code.