Possible causes of electrical faults

WARNING: This page is about a different car, the 2013 BMW 550i GT, 2012 BMW 550i GT, 2011 BMW 550i GT, and 2010 BMW 550i GT. However, it is still accessible from the selected car via links, so may be relevant.

Water in the connector (corroded contacts) → exchange the sensor and connector.
Sensor signal is corrupted by voltage drop. Gradual process
Short circuit (detected by control unit and output as fault message)