After disconnecting the battery on my Ducato x250 motorhome to try and clear a 'Check Engine' warning (which didn't work!), I re-connected it to find some of the warning lights on the dash panel continuing to be dimly illuminated for a few seconds after the ignition has been turned off. In fact, they seem to stay lit for as long as the interior light is on. Anyone know why this would have happened and what to about it? Any help would be gratefully received...

Switching lights on and off is under responsibility of the "chassis computer", a small plastic box above the dashboard fuses. Possibly it was not properly initialized after you reconnected the battery.
Remove power for at least 15 minutes, then connect the battery without hesitation. This resets both the chassis computer and the airbag controller.
The engine warning light can be reset via the OBD2 connector.

The dim warning lights phenomenon is a common Fiat dashboard fault which has been covered extensively on this Forum in the past. I suspect that it is nothing to do with the battery disconnection but was there all along. Maybe you have noticed it because you have recently been looking at the dashbord lights more closely than before? The cure is to replace or repair the dashboard (if under warranty) or to ignore it and hope it doesn't get any worse (if forking out your own cash).

Hi The fault you describe is definitely a panel fault and is a well known fault condition that Fiat are very aware of. Mine was replaced free of charge by Fiat following a claim by the dealer, the motorhome was out of Fiat warranty by 10 months! It was a very quick easy job to replace but very expensive if you have to pay for a new panel yourself.
Best to try and live with it if Fiat will not do the honourable thing! There are companies on the internet who claim they can repair these Fiat Ducato Instrument Panels with faults you describe.