I have just bought an E91 with PDC.
One of the front ultrasonic sensors appears to be missing (might have fallen behind the bumper).
In use, there is a just long (loud) continuous high pitched beep. When you get into the 'red' zone, the tone alternates between a lower and high pitched tone.
Is this how it is supposed to work? I appreciate there must be a fault with a missing sensor - just not sure if the tone thing is correct. It sure is loud and distracting. Can it be turned down ?