Porsche Cayenne Owner's Manual page 240

Limits of ultrasonic measurement
– ParkAssist cannot detect sound-absorbing
obstacles (e.g. winter operation, powder
snow),
– Sound-reflecting obstacles (e.g. glass sur-
faces, flat painted surfaces),
– And very thin obstacles.
Other ultrasound sources (e.g. pneumatic brakes
of other vehicles, jackhammers) can interfere with
detection of obstacles.
Fault indication without warning tone
All red light segments of the active warning indica-
tors light up when there is a temporary fault in
ParkAssist.
Note
Correct operation is no longer ensured if there is
a temporary fault (e.g. caused by ice formation or
heavy soiling on the sensors).
The system detects the temporary fault.
All light segments light up until a speed of
9 mph (14 km/h) is reached.
ParkAssist is ready for operation again when the
interference has been eliminated.
240
Parking
Fault indication with warning tone
In the event of a long-lasting fault in ParkAssist,
the red light segments of the active warning indi-
cators light up and a continuous tone sounds for
three seconds after a transmission range has
been selected.
Possible causes
– Defect or system fault.
f Switch ParkAssist off.
When ParkAssist is switched off, the indicator
light in the button lights up.
Please see the chapter "SWITCHING
PARKASSIST ON AND OFF" on Page 237.
f Please have the fault remedied at an
authorized Porsche dealer.
Driving with a trailer
The ParkAssist rear monitoring area is switched
off when the trailer's power supply is plugged in.