Use a code reader and read codes, clear codes, only after you verify that the ABS sys is OK. Then clear the OBD II codes, drive and see if codes return. It could also be a faulty sensor, or check the sensor connectors. I bet they disconnected the sensor without disconnecting the battery first.

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/ / / Mike
BMW X5 Xdrive50i 2015 F15
BMW 325iC 1992 E30
BMW X5 4.4i - sold
BMW 335i X Drive 2010 - sold
BMW Z4 3.0is 2006 - sold
BMW 325is 1993 - sold
BMW 2002 1976 - sold

X5 Garage