Modern Vespa

Hi , I need some help sorting out this issue . I have an immaculate 2019 GTS with only 300 miles on the clock …I took it out yesterday for a spin after a while in storage , battery was initially a bit flat (lithium type) but after a good ride it's fully charged ( according to the battery's charge indicator) it starts anyway !
Everything was working fine even the Speedo initially but on my way home I noticed Speedo was stuck on 40mph and has not budged since…mileage is still going up , no warning lights…on this bike I can see a sensor , I'd imagine abs front and back but no cable as such…
Does anyone out there know definitively if this model has another means other than a cable and what possibly could be wrong ? Where a loose connection could possibly be ? I did disconnect battery but needle remained blocked …I'm desperate as was about to sell her …many thanks in advance …Steve

The speed signal feeds into the speedo and splits to the odometer and needle, the problem is internal to the speed then. Is your milage going up at 40mph? Might be a spider or something sticking the needle.
Have you taken it on a high speed run to blow the cobwebs out figuratively and literally?

Yes I gave it a blast , Speedo needle is solid on 40mph but the mileage goes up as normal …it was ok one minute then bam !

If the speedo on the 2019 is fed from one of the ABS tone rings (I imagine it is) then the speedo is driven by a stepper motor rather than the analogue spinning magnet system. So either a tone wheel signal has been lost, or there's a duff connection between whatever drives the stepper motor and that motor.

BICBW...

then the mileage wouldn't go up.

True - if they're fed from the same source, which would seem logical. However, one could be fed from one tone wheel, and the other from the other one..