I ran about 2 miles on EV then switched to HV 1/2 mile before getting on the freeway. After about 3miles red temp light came on Outside air temp was about 65. I was on a 2 mile long single lane transition so I was unable to get off the freeway. I slowed down to about 60mph from 70mph the light went off. The light was on for about 2min. I got off the freeway and opened the hood. The coolant had over flowed puking coolant all over my clean engine. I was able to run EV to dealer to check. My guess was a stuck thermostat! Dealer just called me and after calling manufacture to discuss the the error codes and my symptoms, there best guess was a stuck thermostat.
Does Prius Plug-in have a coolant temp display? Prius V doesn't have it but I connected an external one to OBDII port.
No analog type display, just an idiot light. No warning of climbing temp just pow! in your face melt down. I also us a blue tooth OBDII with Torque software on my Android
The Dealer didn't have a Radiator Thermostat for the PIP ??? WOW. By the way, do you Block your Grill?
I Live in Huntington Beach, Ca. So I think its "freezing" and reach for the seat heaters0 when the Temp dips below 65. But to answer your question, I don't block the grill. The day it over heated was a cold day of 68
