Turning the key to MAR the warning light on the dial turns on, but it should go off as soon as the engine is started.
If the 
warning light turns on when
the car is travelling (on certain versions together with the message on the display),
stop the engine immediately and contact a Fiat Dealership.
See also:
Installation of electric/electronic devices
Electric/electronic devices installed after buying the car or in aftermarket
shall bear the and marking:
Fiat Auto S.p.A. authorizes the installation of transceivers provided that installation
...
Anti-Lock Brake System (ABS)
This system aids the driver in maintaining vehicle control under adverse braking
conditions. The system controls hydraulic brake pressure to prevent wheel lockup
and help avoid skidding on slipper ...
Driving mirror
The mirror is fitted with a safety device that causes it to be released in the
event of a violent crash.
Using the lever (A) it can be moved to two different positions: normal or antiglare.
WARN ...