Answer: This issue can be happen for three reason below:
Reason 1: You have done a wrong toolhead switching operation. When you change your toolhead maybe you forgot to change the toolhead from the machine menu and your screen show wrong toolhead.
Please make sure you have changed the toolhead correctly. If you have done this process and still have the problem the move on the next reason.
Reason 2: Maybe your toolhead thermistor is not well connected with your toolhead.
Please dismantle your toolhead and check the wire if it’s connected well. You can remove it and insert again. The test if it’s still showing the same.
Reason 3: Maybe your toolhead thermistor is damaged. You can Replace the thermistor to solve this issue or replace the whole toolhead.