How do I replace a driver's side ABS sensor?

It's built into the front wheel bearing assembly and has an extremely high failure rate. Not because the sensor fails but because of the design they don't produce much of a signal. The bearing assembly develops a little play, which is perfectly normal and common in any car, but that play lets the ABS sensor's signal drop out. The dealer's scrap metal bins are full of these bearings. They can cause problems in as little as 15,000 miles. Funny thing is the non-ABS bearing is the exact same part but without the sensor, ... And it costs more without the sensor. We only buy bearings with the sensor and just don't connect it if the car doesn't have ABS.

You can also use your old bearing on someone else's car that doesn't have ABS. There's really nothing wrong with the bearing other than that normal play that develops. GM has always liked building their parts into big assemblies that go together faster on the assembly line. The drawback is you have to buy more stuff when you replace something. Their generators and their older distributors where other examples of that design philosophy.

No. You buy the entire wheel bearing assembly.