Ford FOCUS 2015 Owner's Manual page 171

WARNING
To help avoid personal injury, NEVER
use the Cross Traffic Alert system as
a replacement for using the interior
and exterior mirrors and looking over your
shoulder before backing out of a parking
space. Cross Traffic Alert is not a
replacement for careful driving.
E142440
In this first example, the left sensor is only
partially obstructed; zone coverage is
nearly maximized.
Focus (CDH), enUSA, First Printing
Driving Aids
168