topic Re: Nest Thermostat error code 257 in Nest Thermostats

Nest Thermostat error code 257

InfiniteRebel83 — Sun, 28 Sep 2025 14:18:52 GMT

Hello my nest says I have an error code 257. I have a red, green, white, and blue wire for my system. The old thermostat had a spot for the blue wire. I have it in the OB slot. Does it need to be moved to the C slot?

Re: Nest Thermostat error code 257

GabrielaG — Fri, 03 Oct 2025 00:24:20 GMT

Hi @InfiniteRebel83,

Thank you for contacting the Google Nest Community. I'm sorry to hear your Nest Thermostat is having the 257 error code. I appreciate the details you provided me about your wiring. I'm glad to help you.

To make sure I provide you with the most accurate and effective troubleshooting steps, I just need a little more information. Could you please answer the following questions for me?

What type of Nest Thermostat do you have?
What type of HVAC system do you have?
When did you install your Nest Thermostat?
Could you please send me a picture of the current wiring for your Nest Thermostat?

If you have any additional details that might be helpful, feel free to share them with me.

Regards,

Gabriela

Re: Nest Thermostat error code 257

InfiniteRebel83 — Fri, 03 Oct 2025 09:49:41 GMT

So I managed to fix the problem. I had to go into the Google Home app and change what the blue wire was from OB to C and that fixed the problem. Then update wiring and bam problem solved. Thanks for the reply tho.

Re: Nest Thermostat error code 257

GabrielaG — Fri, 03 Oct 2025 21:32:38 GMT

Hi @InfiniteRebel83,

Thanks for the update. I'm glad to hear that you resolved the issue with your Nest Thermostat by changing the blue wire from the OB terminal to the C terminal using the Google Home app.

If you have any further questions, please feel free to post.

Regards,

Gabriela