Thermostat: incorrect wiring G wire

Hello crew,

An electrician came to install my Wyze thermostat. He left, and I as was finishing the setup on my phone, got this error message.

I looked at his work, and it does look like he did the right thing:

  • Hooked each wire matching the previous setup
  • Pulled a new wire from another cable to power the thermostat with C (former thermostat is battery)

Here is his wiring

Here is the former thermostat

I proceeded with removing the G cable as instructed by the app. And the AC would work, but manually controlling the fan would not work – which seems the make sense because it seems to be done by the G cable (?).

It’s my first time messing with a thermostat so I might be missing something. Any help?

I don’t have the Tstat, but I believe this could be something to do with how you setup the Tstat. When going through the setup, it asks something about your fan doesn’t it? Maybe you selected the wrong option for that one?

Could be totally wrong, just guessing based off of other posts I have read. Someone will see this who is more knowledgeable on this device soon.

Do you have a heatpump or Natural Gas?

During the setup process it asks you questions about the Type of HVAC and your wiring will be based on what your answer is.

Can you also post a picture of your Furnace Control Board where the wires hook up to?

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The issue is that you need to go back through setup and tell the thermostat that your “old thermostat” has the following wires: R, C, Y, G, W. When it asks for what wires your “old thermostat” uses, what it is really asking is what wires exist in the wall, and this is what determines which outputs it turns on when the wyze is installed. By not telling it that the “old thermostat” has a C wire, it assumes that there is no C wire, and that you have used the C wire adapter, so you must have connected a random wire to G, so it throws an error and doesn’t use that output.


That’s it, makes a lot of sense now that you say it @speadie - thank you for helping to troubleshoot! :pray: