Volvo 2008 V70 Owner's Manual page 169

Rear park assist is deactivated automatically when towing a trailer if Volvo genuine trailer wiring is used.
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04 Comfort and driving pleasure
Park assist (option)
Front park assist
The distance monitored in front of the vehicle is approximately 2.5 ft (0.8 m). The audible signal comes from the audio
system's front speakers.
It may not be possible to combine auxiliary headlights and front park assist since these lights could trigger the system's
sensors.
Faults in the system
If the information symbol illuminates and
indicates that the system is not functioning properly and has been disengaged. Consult a trained and qualified Volvo
service technician.
CAUTION
In certain circumstances, the park assist system may give unexpected warning signals that can be caused by external
sound sources that use the same ultrasound frequencies as the system. This may include such things as the horns of
other vehicles, wet tires on asphalt, pneumatic brakes, motorcycle exhaust pipes, etc. This does not indicate a fault in
the system.
Cleaning the sensors
Park Assist syst Service required is shown on the information display, this