Have you just recently done a front brake job? The reason I ask, is I had the same problem, but the sensor wasnt bad. Trying to save you a buck.
In my scenario, the speed sensor was not making magnetic contact with the rotor because the speed sensor had metal shavings/crud all over it and the part on the rotor had pushed away. It is different on the 04+'s but similar. I pulled the front wheels off, looked at both sides and saw the difference. Pulled the rotor off on the side that said bad speed sensor, adjusted the metal piece on the back of the rotor closer, cleaned off the sensor and it is fixed.
I hope any of this helped.
In response to you actual question, I am not sure. I would think to pull the rotor off for better access to the back.
IIRC the rotor came off because I had to remove the caliper anyways, so why not get the rotor out of the way, it slides right off. Makes for more room to get my big head in the wheel well to work with an air tool.
Is it possible to throw codes, due to needing cleaning as in devildogs scenario? The code would mean something is not right, not necessarly bad sensor. Just trying to prevent replacing something that might not be broke..