Ducati Diavel Carbon ABS Owner's Manual page 88

The key contains a battery that must be replaced when the
low key battery "warning" is displayed as soon as the
dashboard is turned on (fig. 64).
Note
In this case, replace the battery as soon as possible
(page 88).
When the charge level goes below a certain limit, the key can
only work in passive mode, like the passive key: in this case,
the dashboard will not display any message.
Warning
Do not ride with the key (1 or 2, fig. 62) inserted in the
lock of the tank cap or in the seat lock as it could come out
and represent a potential danger. Furthermore, if bumped,
the key mechanism and the integrated circuit could be
damaged.
Also riding in poor weather conditions with the key inserted
could cause damage to its integrated circuit.
Do not leave the key on the motorcycle when washing it as
it could be damaged, not being watertight.
E
fig. 64 fig. 38
87