Usa models are equipped with an additional system with an evaporative emissions canister that prevents fuel fumes from being discharged into the atmosphere.
The breather hose (4) is connected to the canister filter (1); when the fuel has been filtered, it is returned through the hose (2) to the horizontal (a) and vertical (b) intake manifolds via the hoses (2a) and (2b). Drainage pipe (c) and the hose (5) vent to the ground.
For correct positioning of the connection hoses consult the indications given below.

Evaporative emissions canister
Removal of the evaporative emissions canisterEntering pin code function for vehicle release
This function turns on the motorcycle "temporarily" in the
case of hf (hands free) system "malfunctions".
To activate the function, press the "emergency" hands free
button (7, fig. 87) If the motorcycle cannot be turned on using
the normal starter button.
After ...
Checking drive chain tension
Important
Have chain tension adjusted by a ducati dealer or
authorised service centre.
Make the rear wheel turn until you find the position where
chain is tightest.
Set the vehicle on the side stand. Push down the chain at the
point of measurement and release.
Measure the distance betwee ...
Evaporative emissions canister
Sealing washer
Union
Hose clip
Hose
Clamp
"T" fitting
Hose
Support
Special screw
Rubber mounting
Hose
Hose clip
Evaporative emissions canister
Hose
Spring
Spare parts catalogue
Diavel abs evaporative emissions canister
Diavel carbon
abs
evaporative emissions ...