Ducati Diavel ABS 2012 Owner's Manual page 115

The metal part returns inside the grip by pushing it in.
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. 72).
Note
In this case, replace the battery as soon as
possible (p. 114).
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. 70) inserted
in the lock of the tank cap or in the seat lock, as it
could come out and pose a potential danger.
Furthermore, if bumped, the key mechanism and the
integrated circuit could be damaged.
Warning
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 it is
being washed; it is not watertight and could be
damaged.
fig. 72 fig. 38
113