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:
Changing the battery
If required, replace the battery with a genuine spare part having the same specifications.
If a battery with different specifications is fitted, the service intervals given
in the “Service schedule ...
Accessories purchased by the owner
If after buying the car, you decide to install electrical accessories that require
a permanent electric supply (alarm, satellite antitheft system, etc.) or accessories
that in any case burden the ...
Seat Belt Pretensioners
The seat belts for both front seating positions are equipped with pretensioning
devices that are designed to remove slack from the seat belt in the event of a collision.
These devices may improve t ...