I have had the dash light up several times and the rpm's rev up and had to restart and clear codes with scan gauge 11. Poa 80 and another time poa 78 dtc's I was told it was hv ecu so I bought a used one from Autobeyours but was told that this hardly ever is the fault. I have 84=k on 2006. I mostly short trip But on longr drives 30/40 miles is when this happens.I was told thet the soc gets too high and it is natural for the ice to burn this off. I have a scan gauge and the last times this happened I know th soc was about 60% The soc varied radicallt and went up fast as brakes were applied I have an appointment witl Toyota Of Kingsport to replace hvecu but I wondwer if it is still in warranty Help
Here is a link to show you how to test the 12 volt battery. When you start getting weird errors, I think of this first. (because testing it is free and DIY) Weird stuff happening? MPGs dropping? Test The Battery | PriusChat
Assuming the 12V is OK, having the battery SOC change radically as you say, with a P0A80 DTC, sounds more like a failing HV battery. While it is a little soon for yours to go, but there have been cases of this happening in hot climates especially. (I know VA can be pretty hot at times.) The engine does spin to avoid overcharging on long downhills (B mode), but the engine will also run more if there is a weakness in the inverter (as when it is overheating) to protect it. How is your inverter coolant pump? Has it been replaced? As for the P0A78, it would be good to know the freeze frame data, as that points at motor-gen A, but it can fail in several ways. It would also be good to know what sort of temperatures you see in MG1 and MG2, and in the inverter.
