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:
(C) Injecting TIREFIT Sealant Into The DeflatedTire
• Always start the engine before turning ON the TIREFIT kit.
NOTE: Manual transmission vehicles must have the parking brake engaged and the
shift lever in NEUTRAL.
• After pressing the Power Butt ...
Front light units
The front light units contain: sidelights, dipped beam, main beam and direction
indicator bulbs.
The bulbs are arranged inside the light unit as follows:
(1): sidelights/main beam headlights;
( ...