Monitoring overview - sensor diagnosis
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 BMW Z4, 2008 BMW X5, 2008 BMW X3, 2008 BMW 528xi, and 2008 BMW 528i. However, it is still accessible from the selected car via links, so may be relevant.
Sensor diagnosis is performed internally to the ECU and checks the sensor supply voltage to tunable boundaries. A sensor signal versus an internal sensor self check will determine the integrity of the sensor.