I agree with you about not wanting to install the sensor yet. Electronic parts can rarely be returned once they've been installed. With the CEL, ABS, and Brake lights on, I'd be wanting to know what codes I'm dealing with before I go throwing a bunch of parts at it.
Parts store should be able to read the codes and then tell you would need to do to fix them.
Once you've fixed what the codes said was wrong, do a hard reset (disconnect the battery for a min or more) and see what happens.
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