Position seal (18) in tank cap (10) as shown and reassemble following the removal procedure in the reverse sequence.

In particular tighten the screws (17) to a torque of 3 nm +/- 10% (sect. 3 - 3, Frame torque settings).

Removal of the fuel tank filler cap
Replacing the tank flange and fuel sensorAccelerator position sensor (throttle grip)
Introduction
An accelerator position sensor (aps) is mounted on the throttle body of the
diavel, which measures the degree of aperture
of the throttle grip.
The throttle grip is connected to the sensor via two metal cables
The sensor transmits information to the ecu relative to the "torque ...
Riding mode set indication
This function indicates the "riding style" set for the vehicle.
Three "riding modes" are available: sport, touring and urban.
Each riding mode can be changed using the "riding mode" function.
Note
The background of the riding mode (sport, touring or urban) is blue (1) if
currently set ridi ...
Removal of the fuel tank filler cap
Remove tank covers (sect. 5 - 2, Removal of the fuel tank fairings).
Remove hoses (8) and (15) from the filler cap assembly (10).
Open the filler cap.
Unscrew the outer screws (17) securing the ring nut to the filler cap recess.
Remove the filler cap assembly (10).
...