How do you change rear wheel bearing on a 2004 nissan sentra

A wild guess, the "bearing locking nut" device is not properly installed and the bearing nut has backed off. Torque on locking nut not high enough.
Double check by jacking each side push in on top, pull on the bottom if there is any play it confirms my suspicions. If you did not get locking device with the new bearings (a special nut) you probably used the old nut with no way to "Lock" after you removed it. No lock is a dangerous situation! you could lose a wheel and cause an accident!

Bad knock sensor or rod bearing/main bearing failure.

How are the tires? New? Old? Rotate them and see if noise goes away. Possibly front wheel bearing in the front drive axle where it goes thru the hub and rotor.......goes the noise get worse if you turn right or left slightly when driving it? If it gets worse on one side that is the side with the bad bearing.....replace as needed.

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jack the rear of the vehicle up, spin the wheel by hand, and put your free hand on the strut spring, if a bearing is bad , the roughness should travel through the suspension and you can feel it most amplified in the spring.

it may be the rear wheel bearing is faulty & needs to be replaced.........cheers.

That loud humming noise you are hearing is the wheel bearing. After hitting the curb the bearing took a hit and became a little wobbly and over time the grease has seeped out and started causing the humming.So just replace the wheel bearing and anything else that might be loose or damaged like the tie rod and ball joints. if those issues are not corrected it might happen again down the road. good luck and glad to shed some light on your issue

Most newer cars have a bearing that is pressed in to the hub. In order to do the repair you should have to replace the entire hub. This is actually easier and cleaner because the bearings are lubed, sealed and pressed in the hub. They usually cost around $30 and should be available through your local parts store. In most cases the hub is held on by a large nut so I recommend that you make sure you have a socket that is large enough.

This is just because of the warned out wheel bearings just replace the bearings of the rear wheels to sort out this issue.

rdfairfield: if you are asking about the rear? Yes, that is the only way the part comes and is manufactured. It is a hub and bearing assembly..

Easy job ! just rem to get a gear puller for the antilock gear and install same as came off old one Parts around 100$ each apx 1/2 hr each side