P1121, P1116, Changed Coolant Valve, now Red Triangle

Read this thread: 2007 Prius P1116 code and coolant control valve issues | PriusChat

 

That's not a check engine light that's the Master Warning Light. I wouldn't drive the car far until you pull the codes. The car ain't kidding when it throws that one.

How did you change the valve? Did you duckbill off the hoses or drain the entire coolant?
Where does the coolant look full? Overflow or rad? The overflow is meaningless you must take the plastic cover off and open the rad cap to check the real coolant level.

If you drained the entire coolant it is very difficult to bleed the air. I'm pretty good at it and have a ulift and still struggled when I did mine. The trick is to power cycle on the CHRS thermos as you bleed as air tends to get trapped in the thermos and at the top of the engine. Patrick Wong had a cool get around by pulling the CHRS relay and paper clip jump out the relay 12 volts acorss it to force the thermos to cycle a few times. I missed that on my bleed and it made a bleed difficult.

This car is weird about engine overheat also. Sometimes it throws the master light but no one every reports the true overheat icon which is the thermometer in red.

 

This is a great tool for burping the coolant:



Thanks to Patrick I ordered one of these and it is a huge time saver and coolant saver. It attaches directly to the radiator and holds about 2 pints so you can squeeze the coolant hoses and burp out the air. You can also jump the coolant pump relay and run the coolant pump.

 

Most water pumps seep a small amount through the weep hole. Verify that it is actually leaking. This may be something that can be put off for a while. Keep an eye on the overflow tank and see if you are losing coolant. It may be hard to tell because depending on how well they bled your cooling system it may still burp a few air bubbles over the next week or so.

 

its an old post but I am sharing my exact same experience and an easy fix. I had p1121, got coolant control valve changed by a friend who is also a mechanic. The car ran fine for a few days then when I went on the freeway, the red triangle started to go on and off intermittently. It also threw a new P1150 code.I had the doubt that it was coolant related because I saw the mechanic drain a lot off coolant which he said he had refilled.

I always have a bluetooth OBD code reader connected to my car, so i fired up torque pro app and saw the coolant temp was 230F. I didn't know what should be the normal range at that time. Drove a bit slow and came home fine. Next morning, checked the radiator and sure enough i couldn't see coolant in it. Luckily, i had the coolant bottle laying around. Did some more online reading on how to bleed coolant with many suggestions most of which were overwhelming.

Until now it was all the background. here is one of the easiest fixes you would find.
First I opened the radiator bleed valve exactly three turns. This is located under the panel on the right side of the radiator and requires a hex key to loosen. Then opened the radiator cap, turned the engine on and set the fan at high speed and in the heat setting. Then slowly started filling coolant in the radiator. It took about 1.25 Liters and finally i started to see the coolant level coming close to full. Then I went inside the care, and slammed the accelerator in the idle position, went back and saw coolant level dropped again, topped it up again. I also saw that increasing the RPM cranked the pump and there was a little coolant that started to come out of the release valve, which was a good thing and confirmed that there was no more air. Finally, replaced the radiator cap and done.

Overall it took 15 mins to do all this. Ran the car again on freeway and coolant temp was steady at 85F, and no triangle or any other error. I dont know why people suggest to short start the water pump, or connect a hose and bring it back to the reservoir and what not. Its all daunting info floating around. For DIY, i found it sooo much simpler than i thought.