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:
29. Speedometer
The Speedometer shows the vehicle speed in miles per hour (mph) and/or kilometers
per hour (km/h). ...
Rear light unit
To change the bulb, proceed as follows:
❒ from inside the car, remove the upper plastic cover (A) with the screwdriver
provided to reach fastener (B);
❒ from inside the boot, fit ...
Information on standard screen
❒ Date (A).
❒ Total odometer (B).
❒ Clock (C).
❒ External temperature (D).
❒ Speedgear or Dualogic info display (where provided) (F).
With ignition key remo ...