Lincoln 2016 MKZ Owner's Manual page 216

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 or snow is interfering with the radar signals.
Swirling water, or snow or ice on the surface of the road may interfere
with the radar signals.
You are in a desert or remote area with no other vehicles and no
roadside objects.
Due to the nature of radar technology, it is
possible to get a blockage warning with no
actual block. This happens, for example,
when driving in sparse rural or desert
environments. A false blocked condition
either self clears or clears after a you restart
your vehicle.
Cruise Control
Cause
Switching to Normal Cruise Control
Normal cruise control does not brake
for slower vehicles. Always be aware
of which mode you have selected and apply
the brakes when necessary.
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 free from obstruction.
Do not use the system in these conditions because it may not detect
any vehicles ahead.
Do not use the system in these conditions because it may not detect
any vehicles ahead.
Wait a short time or switch to normal cruise control.
WARNING
I n f o r ma t i o n P r o v i d e d b y :
213
Action
You can manually change from adaptive
cruise control to normal cruise control
through the information display.
The cruise control indicator light
replaces the adaptive cruise
E71340
control indicator light if you select
normal cruise control. The gap setting does
not display, the system does not
automatically respond to lead vehicles and
automatic braking does not activate.