The range readout on my trip computer has started playing up (Vectra V6). It starts off ok when you turn the car on, shows 40 or so miles, whatever is remaining, then within a few seconds of pulling off it just drops right down, goes to 5 or 6 miles remaining all the way down to zero as I'm driving and just stops there. The normal needle based fuel guage appears to be working ok. Any idea what the most likely suspect is, a malfunctioning computer, sender, connection or something ?