Depending on the length of time the power was interrupted, your system may require GPS initialization.

If initialization is not necessary, the system proceeds directly to the Startup Confirmation screen.
If the system fails to locate a sufficient number of satellites to locate your position within 10 minutes, the following screen is displayed.

If you are experiencing GPS reception problems:
System Initialization
The navigation system must be initialized if
power to the navigation system is
interrupted for any reason (e.g., the
battery was disconnected). ...
Resuming Your Trip
Stop your vehicle en route (e.g., to rest, stop for gas, etc.), and then
continue on
your route.
If you did not complete your route, the Continue Trip screen is displayed when
you
restart you ...
Dust and Pollen Filter
On models with A/C
This filter removes the dust and pollen that is brought in fromthe outside through
the heating and cooling system.
Have your dealer replace the filter when this service is indic ...