Sony CDX-GT56UI Operating Instructions (CDX-GT56UI) Operating Instructions Manual page 3

Warning if your car's ignition has no
ACC position
Be sure to set the Auto Off function
(page 19). The unit will shut off
completely and automatically in the set
time after the unit is turned off, which
prevents battery drain. If you do not set
the Auto Off function, press and hold
 until the display
disappears each time you turn the
ignition off.
3