Overheat issue with leak after coolant flow control valve replacement

I really need help! I just did the break actuator and coolant control valve a few weeks ago at a shop $$$$ started getting the red triangle of death intermittently after the service only on the highway and now I just realized there is no coolant in the engine reservoir and no sign of it in the opening of the radiator. I am now worried that I blew the head gasket just weeks after these services.

Code P1121 was found. Shop replaced the coolant flow control valve. In their estimate it said 'circuit stuck (for hybrid inverter)' this may be a really green question but seeing that the systems are two distinct cooling systems and they are emphasizing the inverter here can someone tell me if the valve is connected to both? Do you drain the engine system when doing this service? It certainly looks like it to me but I don't quite understand. If I miraculously have a major coolant issue right after this service is it possible that they only worked on the inverter side? The inverter tank still has coolant in it.

I need to know as I may have blown my head gasket and I'm taking it back in tomorrow and want to understand if they are possibly at fault. Should I bring it to someone else?

Here is the rundown

-Every time I was on the highway after the service which was 4 times total the red triangle came on
-First two times it just blinked a couple times but did not stay on
-Last two times longer sustained triangle death but still off and on
-All 4 times I was not on the highway for more than 5-7 minutes.
-I brought it back to the shop after the first two times but they didn't get a reading either and saw nothing wrong. Didn't have tech stream I guess.
-I have ODBii but did not get any codes. I even drove on the highway with it plugged in and tried to read while the light was on and it got nothing.
-My dash screen has been out for over a year, learned to live without it and thought erroneously that nothing major would display on it like an overheat symbol which I guess randomly (thanks Toyota) goes on that screen
-Essentially I just didn't know what was going on and did not head over to Toyota for a reading.
-I was consistently basing my understanding of whether I had coolant based solely on the inverter reservoir and was unaware of the engine reservoir behind the radiator. I know....dumb.
-When I realized it existed I saw the tank was empty and down spout didn't have anything at the top several inches at least.
-After the last time the triangle was going off. I quickly plugged my ODB in and looked at the coolant temp and the light had already come off but the temp was reading like 227 so that checked out for possibly just recently falling from the 240-250 zone and thus my panic set in concerning the head gasket.

I am going to try to top off this bastard in the morning and get to the bottom of this.

Is it likely the coolant flow control valve replacement service is the culprit? All of this literally happened right after the service.

If so, do I bring this to them and see what they have to say or do I go to someone else and confirm the issue.

I told them over the phone yesterday about what I uncovered over the weekend after bringing it to them.

I thought that the service they did was on the inverter cooling system and therefore this problem with the engine loop would not be related to the service. I said as much on the phone with the actual mechanic who did the service and the mechanic concurred with me. I don't know what to think now. They have been a super rad shop. Any clarification would be so helpful if in fact the head gasket is blown.

 

Thank you Tombukt2, can anyone tell me if there are flow control valves for both systems? I'm still trying to understand if this recent service is the reason for my issues. If there were air bubbles in the system post service could they create pressure that would evacuate a lot of coolant out of the system? In my bio it says 2009 Prius but just want to make sure it's in the thread.

Thanks!

 

Thank you! Is it connected to both systems? I understand checking but do both systems need to be bled properly when replacing the valve? I'm confused why the inverter side is highlighted in the workup. Also, can you bleed the system properly without tech stream? At this point I am concerned that A the mechanic seemed to think his work had nothing to do with that part of the cooling system which seems like a red flag and B he's working on it again right now and I feel like its not likely he will bleed the system correctly if he doesn't know all the intricacies involved.

 

I super appreciate the clarification here. It makes me pretty concerned about all of the work that was done. Including the actuator... the bleeding process for that is intensive and also reliant on Techstream?

My screen has been non functioning for a while now. Does inspection mode directly work with the screen? Can this process be done in another way?...I definitely did not realize how software dependent this situation is. Thanks again for your reply. Anything I can do to double check the actuator while I'm at it?

 

Um, so...the control valve does not even interact with the inverter coolant system?? How does a mechanic get them confused who has already done the service? SMH

 

I mean, other then the brakes failing, is there any signs I could look out for in regard to a bad brake bleeding being done?