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 temperatureRefitting the brake disks
Before refitting the brake disc to the wheel, clean all contact surfaces
thoroughly and smear a medium strength
threadlocker on the threads of retaining screws (5).
Operating on the left side, fit the phonic wheel (6).
Tighten the fixing screws (5) of the brake disk (7) to the wheel followi ...
Horn not working
Fault codes
Dds: horn diagnosis -> short circuit to ground (s.C. Gnd).
Dashboard: the error "claxon" (horn) is shown on the service display. The eobd
warning light activates.
Wiring diagram
Db dashboard connection, s horn button. 5 Blue/white - b/w, 1 red/blue - r/b,
db 19 purple/bl ...
Passive key
Introduction
The passive key (1) is used when the active key is not working correctly or
is not available.
The passive key works as a transponder, and must therefore be placed physically
onto the antenna to work.
The mechanical part (2) of the key is used to open the seat or the tank plug ...