Hi
The part in the photo looks like Fiat OE part number 5802052418. If you Google that, you will see it described as:
Damp Heater
Heater LT
Pipe
Oil Return Pipe
Turbo Temperature Heater
Electronic Sensor
Hose Sensor Temperature Oil
In other words, most of the people selling these (either new or used) don't have much of a clue as to what it does ! Even the Fiat parts system can often have pretty vague descriptions.
I did find a photo which shows it attached to a throttle body just upstream of the air input to the turbo. I am fairly certain therefore that this is indeed the pipe which recycles unwanted oily "blow by" vapour from the engine back into the air stream to be eventually burnt. Under very cold weather conditions it's possible for the water vapour component of this flow to turn into tiny ice crystals, which doesn't do the turbo blades much good. The heater is there to melt these and prevent this problem.
Your fault code indicates a possible fault with this component, so it's probably worth changing it. If you can buy just the centre part it might be cheaper and you could re-use the hoses, but you may find you can only buy the whole assembly.
In older Ducatos this was a 20 watt PTC thermistor type heater plain and simple, with only 2 wires. I have no idea if this later part has extra sophistication in the form of valves or sensors.