Hi Em, the only warning sign I can see in the handbook with stop on it, is an octagon for a powertrain breakdown.. This is only a guess, but the Overseer module is a possibility to consider, as there have been a few reported weird issues that ended up fixed by replacing this module.. The early Plus Six seem to had a few replaced, ours included. After we first purchased the car, the car came to a halt at traffic lights coming off a motorway while in gear, would not restart with engine management light on, then display went blank, after several ignition on/off the normal display came up and the car restarted with no sign of any issues. The dealer found nothing wrong with no fault codes recorded at that time, they remade most if not all the main earths after talking to the factory, after that the car came up with a Overseer fault. The module was replaced and touch wood ok since..
I guess it would be worth a quick trip to the dealer to see if any fault codes are recorded.
