Ford 2011 Explorer Owner's Manual page 303

Driving
WARNING: The collision warning system's brake support can
only help reduce the speed at which a collision occurs if the
driver applies the vehicle's brakes. The brake pedal must be pressed
just like for any typical braking situation.
Blocked sensor
If a message regarding a blocked
sensor is displayed, the radar signals
from the sensor, located behind a
fascia cover near the driver side of
the lower grille, have been
obstructed. When the radar signals
are obstructed, a vehicle ahead
cannot be detected and the collision
warning system will not function.
The following table lists possible
causes and actions for this message being displayed.
Cause
The surface of the radar in the
grille is dirty or obstructed in
some way
The surface of the radar in the
grille is clean but the message
remains in the display
Heavy rain, spray, snow, or fog is
interfering with the radar signals
Swirling water, or snow or ice on
the surface of the road may
interfere with the radar signals
302
2011 Explorer (exp)
Owners Guide, 1st Printing
USA (fus)
Action
Clean the grille surface in front of
the radar or remove the object
causing the obstruction
Wait a short time. It may take
several minutes for the radar to
detect that it is no longer
obstructed
The collision warning system is
temporarily disabled. Collision
warning should automatically
reactivate a short time after the
weather conditions improve.
The collision warning system is
temporarily disabled. Collision
warning should automatically
reactivate a short time after the
weather conditions improve.