The activation of this (amber yellow) "warning" indicates that the hands free system has detected that the battery that permits the active key (1, fig. 62) To communicate and turn the vehicle on is almost discharged.
Note
In this case, ducati recommends replacing the battery as soon as possible as described in the paragraph "replacing the active key battery" (page 88).

Hands free key (hf) not recognised
High engine coolant temperatureCommunication antenna
Introduction
The communication antenna enables the hands free system to detect and
communicate with the active or passive key.
The active key is detectable within a range of 1.5 Metres, whereas the passive
key (or active key with flat battery) can
only be detected if placed in contact with ...
Introduction to the "hands free" system
The hands free system allows the rider to start the engine without physically
using the ignition key. The ignition key
merely has to be in the vicinity of the motorcycle, such as in the rider's
pocket, for example, in order to use the vehicle.
Compared to the standard ignition switches the h ...
Spark plugs replacement
Check the colour of the ceramic insulation around the central electrode:
an even, light brown colour indicates the engine is in good condition and
running at the right temperature.
Inspect the centre electrode for wear and check spark plug gap, which should be:
0.8+/-0.1 Mm.
Important
...