The turbo solenoid or boost valve is used in a number of Fiat Vehicles, this guide is as a result of reading a number of threads about it, including a Stilo thread where it is relocated because of water ingress, so beware of Ducato scuttle issues.

There is a specific option to test the (turbo solenoid)boost valve in multiEcuScan.
turbosolenoid-test.png

Just select the test (Ignition on, engine off) press F10 or click execute and it will signal the valve to open and close a number of times. You should be able to see and hear it. At the same time the turbo actuator rod should move a few time untill the vacuum is used.
If it works at least one time the valve is OK, less than 3-4 times check the vacuum pipes.

with a x250 and x290 can see turbo actuator from bellow.

This is a Turbo solenoid
solenoid.jpg


the replacement of a turbo solenoid on a 2017 Ducato is discussed here