I'm not sure, i've not owned or driven a Fiat with Dualogic before. There will be others that can assist though, hopefully someone will be along shortly to advise where to check the fluid.
Issues like this crop up a lot, so there will be someone with the correct advice to help.
ArthurM
the gearbox is termed a dualogic..there are HUGE threads covering it's Pro's + Con's on the forum,
it's basically a normal manual g-box,
but with a ROBOT working the clutch , and shifting gears for you..,
so - the gearbox is just that - it will require GEAR OIL ,
and has a level plug halfway up it..,
AFAIK there is NO FILTER here.., - (did you have ENGINE oil and filter changed..??)
sat on the upper front edge of the 'box is a clear plastic reservoir ( often under an alloy "baking tray")
this contains the actuating fluid for the "robotics" ( selespeed fluid)
the level CAN drop and cause issues,
however there are several trains of thought about the CORRECT LEVEL to attain..
the system can require periodic bleeding / purging of the fluid around it's closed loop system,
done with electronic software - from the comfort of the drivers seat..!!
that's the basics of the system
However , your issue sounds like a dip in electrical power causing several sensors to report "low voltage".
in your shoes I would;
have a quick look under the bonnet ,
make sure there are no large puddles around electrical fuseboxes..
wiggle battery terminal connections
test battery voltage COLD - should be 12 V +
start engine , check battery voltage with it running , should be 13 V +
as long as nothing is OBVIOUSLY amiss ,
I would not be too concerned..
IF it does it again,
consider plugging in a fault code reader - just to see what the vehicles "Brain" thinks the issue may be,
Charlie - Oxford