I have a 2009 Prius. Recently it shows red triangle and check engine sign. I went to a shop got a scan. It says the cooling of the battery is the problem. Not sure it is the fan or coolant too low? Appreciate help
is the problem an inverter pump failure? If you went to a shop that left you thinking it's either coolant or fan, it probably wasn't a mechanic shop?
if cooling of the battery is the problem then cleaning the hybride battery fan might help. there are videos on Youtube explaning how to do this if you are a handy person.