Loss of coolant 2017 prius, headgasket??

welcome!
it's usually at the exhaust coolant heater loop. i think there is a tsb or extended warranty. call a dealer, or log on to toyota.com/owners

 

This USA TSB might not cover you due to the mileage limit, but it might. Search to see if there is a Canadian version of this TSB. Good Luck.

I had this occur on my 2017 Three Touring. It was the exhaust coolant heat exchanger. Took a while for the parts to come in, but was fixed under warranty.

See attached...

 

Are you sure it's the coolant you keep refilling? Or the washer fluid? If it's the coolant, I'd suspect someone never changed the fluid and would probably take a really close look at the water pump. The worse case scenario would be the head gasket. But you should see telltale signs of that, white smoke in the tailpipe especially after start, milky oil, etc.

 

What bisco said.
Very common

 

please let us know the dealers response

 

Did they do a pressure test?

 

I can see the exchanger at the throttle body being a source of a leak and hard to find as well.

 

See TSB T-SB-0135-19 - I didn't know I was losing coolant. it was an internal leak and fried the engine. NO WARNINGS Nothing the car just lost power. It gave me a "Hybrid System Stopped Steering Power Low" right after I suddenly lost power as I turned into a parking lot. I had it towed to my house, hooked up an OB scanner, got a P3190, and replaced 12V battery with no change. The dealership has it now installing an engine, water pump and exhaust to the tune of $10200.00 The car has been very well maintained since new. All servicing has been done at Toyota, where I bought new in 2016. The car gave no warnings whatsoever. I suddenly started losing power and then displayed "Hybrid System Stopped Steering Power Low" and "contact the dealership". You would think if the car was low on coolant or out, the car would give you a notification (IDIOT Light) that the car was getting hot.

 

See TSB T-SB-0135-19 - I didn't know I was losing coolant. it was an internal leak and fried the engine. NO WARNINGS Nothing the car just lost power. It gave me a "Hybrid System Stopped Steering Power Low" right after I suddenly lost power as I turned into a parking lot. I had it towed to my house, hooked up an OB scanner, got a P3190, and replaced 12V battery with no change. The dealership has it now installing an engine, water pump and exhaust to the tune of $10200.00 The car has been very well maintained since new. All servicing has been done at Toyota, where I bought new in 2016. The car gave no warnings whatsoever. I suddenly started losing power and then displayed "Hybrid System Stopped Steering Power Low" and "contact the dealership". You would think if the car was low on coolant or out, the car would give you a notification (IDIOT Light) that the car was getting hot. have dealership check the part number on the exhaust

 

I remember driving DIL's Sunfire to Costco for tire repair, looking at the dash, muttering "Even this POS has a temp gauge"...

 

Sounds like the head gasket failed, likely due to manufacturing defect. Reduction of power would be it getting hot or the coolant mucking up the bearings on the crankshaft and or both. Eventually, engine will fail in such a scenario.

 

it was the exhaust heat exchanger causing the "internal leak", not the head gasket.

 

It might be?

 

the poster referenced TSB T-SB-0135-19, which is the one about exhaust heat exchanger failure.

 

Do diagnostics=No diagnosis

 

Did you even get a diagnosis? I have the same car, same miles and same problem. A few trips to the dealer. No fix. I’m at a loss.

 

sounds like the heat exchanger. dealers are clueless

T-SB-0135-19

 

I agree - they are clueless! I did share the service bulletin with them and they said they didn’t see any coolant in the exhaust system. Yesterday I took a long trip and saw puffs of white smoke on hard acceleration. I am adding maybe a cup of coolant a week! Should I take it to a independent mechanic and have them do the bypass?