High Coolant Temp Warning Flash Then Off

2013 Prius V
176,000 miles

Driving on the highway I noticed the High Coolant Temperature warning light flashing for a few seconds and then turn off. I have only seen this happen this one instance. I had just put the car in Power Mode to quickly accelerate from 45 to 65 mph but then put it back in Eco Mode and was driving at 65 mph. I don't normally switch drive modes and so I of course am wondering if the two events are correlated. Coolant level is fine and holding steady. (I check it about once a month or two.)

I flushed coolant and transmission fluid at 101,000 miles. No parts were replaced at that time, just fluid.

Is this a sign that something is about to fail? Is there something else I should check? Or should I wait and see if the warning happens again?

Thank you all!

 

Greetings! Yesterday while driving my 2013 Prius V, I saw the Hot Coolant indicator flash for 2 seconds then come on solid. I heard a sound like pressure releasing, which I later discovered was coolant spewing past the fill valve. The coolant indicator then turned off and the check engine light turned on.

The only visible issue I see is that coolant sprayed out of the reservoir (the one on the passenger side of the engine compartment). There is still a lot of coolant remaining, just a bit below the Low line. I had not been leaking coolant before this.

Haven’t figured out yet what the error code is. Curious what you think the problem might be. Thanks!

 

Codes are for failed water pump, failed thermostat, and shorted temperature gauge. You all were spot on with your assessments!

 

Yes, I was following your advice and checking the levels a twice a week. That issue did not recur until now when it appears the pump failed

 

Oh, you’re right. It was a different user who posted after you that recommended to monitor the coolant levels regularly. My mistake.

I don’t own the device to read error codes. I relied on a service center for that. My hope from the discussions here in PriusChat is to get a second opinion and try to learn from others’ similar experiences. You and the other users rightly tipped me to the water pump. I think the lack of leaking fluids corroborates that conclusion even without knowing the error codes.

I also see now, if the temperature monitor is shorted or otherwise failed, that it was a mistake to rely upon dash indicators to tell me if the coolant was hot rather than buying the Bluetooth device you recommended.

 

Are you recommending I replace the head gasket along with the water pump?