P1121 Replacing Inverter Coolant Valve Bleed Order

Your saying inverter coolant that’s a separate loop from the engine coolant. They have nothing to with each other. The 3 way valve is engine coolant.

For future lurkers its best to duckbill off the hoses when replacing anything in the engine coolant loop so not to invoke air into the engine coolant loop since it is a real hassle to bleed. The real hassle is the CHRS canister.
You can buy duckbill Pliars at harbor freight cheap.

To guid you might as well dump the whole system now since you got air in it.
Make it worth your while, dump the rad then open the engine bleed valve which is on the backside of the engine right below the exhaust manifold.
That will dump all the engine coolant. Then dump the rad.

Then fill the rad back up disregard the over flow tank it’s useless .take the top black plastic cover off the radiator and open the rad cap.
Fill it back up with Toyota LLC coolant.
Open the hex port on the side of the rad top on the drivers side.
Fill the rad up start thecar and open the hex port to let air out.

Then find the CHRS relay and jump out that relay to cycle the CHRS pump at intervals. So it’s a dance between the side hex port and the CHRS cycle.
Cycle CHRS pump a bit then open hex port to let air out.

As engine warms up check in and out rad hoses for equal temperature.

It’s best to have like a scan gauge where you can check the engine temp
As you go along. Without one you will have no idea how hot the engine is so pay attention to hose in and out heat

You over heat a g2 it will blow the head gasket.

Ridiculous there’s no engine temp gauge.

Good luck.