Did I cook my brand new HV battery

This code relates to the engine coolant loop. You said you ordered a new coolant flow control valve (CFCV) but don't say if you actually changed it when you got it originally. There is not much to the diagnosis and repair is usually to replace the CFCV if your diagnosis does not reveal any clogging in the coolant loop.

If you have changed the CFCV with an OEM part, then most likely you have a clogging issue somewhere in the loop. If you bought an aftermarket part, it is possible it failed already.

P1121 | Coolant Flow Control Valve Position Sensor Circuit Stuck

Areas to look at:

• Water valve (coolant flow control valve)
• Cooling system (clogging)

 

If the valve was changed verify that the hoses were put on correctly. It is very easy to swap the top two.

There is always the possibility that the replacement part was bad. It shouldn't happen often with a Toyota part, but sometimes even good manufacturers ship parts which are either DOA or fail in very short order.

Check the electrical connector to the valve. I don't recall if a bad (open) wire gives the same code. Still, connectors can become corroded or a wire can pull out of a pin, and then the valve won't work. I think this part and the wiring to it can be electrically tested using Techstream to set its state and then measure voltage on the pins at the connector, but I don't have access to the manual right now, so cannot be sure.

There is a procedure to get the air out of the engine cooling loop after changing the valve. The initial part is pretty quick, but coolant will need to be added for a few more days before it is all out. Don't skip those steps!

 

OEM from the dealer, or OEM from Amazon or Ebay? The web vendors are awash with fake "Toyota OEM" parts.