The warning light on the dial turns on (on certain versions together with the message on the display) when one or more doors, the boot (indication fitted on some versions only) or the bonnet are not properly shut.
Symbols 
shown on the multifunction
display indicate incomplete left/right door closing.
With doors and boot open, if 4 km/h speed is exceeded the buzzer will sound (only for versions with reconfigurable multifunction display).
IMPORTANT On versions not fitted with electric door lock, no warning message will be displayed if door is not perfectly closed or is left open.
See also:
Emergency start-up
If the Fiat code cannot deactivate the engine immobilizing system, the warning
lights stay on and the engine will
not start. Follow the emergency start-up procedure to start the engine.
Read the ...
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
...
If an exterior light burns out
Alterations or repairs to the electric system not carried out correctly and
without taking into account the system specifications may cause failures and the
risk of fire.
See “If a bulb burns ou ...