Bad wiring, stuffed sensor or bad connection
Look at the LH connector as well that is in the engine bay. When you buy a sensor now, I understand the wire runs from the wheel to the control unit, getting rid of the connection (and perhaps another fault point.) Clean it up and use some electrical connection cleaner lubricant (available from Jaycar) to clean it up some more and get a better connection. Also useful for the selector switch for the auto and lots of other electrical connectors / switches.