The Iveco-built 2.3litre 150bhp motor initially became available in Ducato “X250" vehicles in mid-2011 in Euro 5 form.
In mid-2014 the Ducato X250 design was facelifted, The revised range was now generally referred to as “X290” and the Euro 5 150bhp motor was tweaked, with Fiat calling its emissions standard “Euro 5+”.
In mid-2016 the 150 motor became Euro 6-compliant.
A potential identification problem with motorhomes is that there will almost always be a delay - sometimes a very long delay - between when the base-chassis is delivered to the motorhome converter and when the completed motorhome is eventually registered and sold retail. So Chris’s 2017 motorhome’s 150 powerplant might well be Euro 6-compliant, or its Ducato chassis might have been made prior to mid-2016 and its 150 motor would then be Euro 5+ (like the the 150 motor in my own Ducato-based motorhome).
I doubt it will be important if the emissions standard of the 150bhp motor in Chris’s Ducato is Euro 5+ or Euro 6 as the hot-starting problem he has described is clearly not normal. As I said above, I have not come across anything anywhere else about hot-starting problems with recent Ducatos.
The Iveco-built 2.3litre motor is fitted to Fiat Ducato and Doblo (installed transversely) and Iveco Daily (installed longitudinally). As far as I am aware Ducato, Doblo and Daily are the only European applications for the 2.3litre engine.
Chris could try asking about this on the Fiat Forum, and/or on the MotorHomeFacts, MotorHomeFun and OutandAboutLive motorhome forums, with the last motorhome forum probably the best for an expert technical discussion.
If Chris seeks advice on other forums, expanding his enquiry should allow for more focused feedback. Selecting from the following should help:-
1: Make, model of motorhome (assuming it is a motorhome Chris has!) and its current mileage.
2: Confirmation that its motor is Euro 6 or Euro 5+.
3: Vehicle transmission - manual or ComfortMatic.
4: When the hot-starting problem first showed up. Had the Ducato always done this or, if not, when did the behaviour commence? Had anything significant happened (like a service or under-warranty work being performed) not long before the hot-starting issue began?
5: What was the Fiat Professional-installed software revision supposed to have done? (eg. Modify the fuel injection programming.) When was the software revision carried out?
6: Is the hot-starting difficulty still happening? If so, how regularly is it occurring?
7: What possible explanation (if any) has the Fiat Professional agent given?
8: What has Fiat Camper told Chris to do if the problem persists? (Hopefully Chris has a Fiat Camper reference, emails, etc. proving that the issue commenced within the Fiat 2-year warranty period but could not be successfully cured.)