Nest thermostat E 294

[clancymart]

I have a basic Nest thermostat. The old thermostat had 4 wires connected: GREEN, RED, YELLOW, WHITE. I connected them to the designated terminals on the Nest I got Error: E294 message and Safety off message. I discovered that there is a 5th wire (blue) that was not connected to the old thermostat. Could that be the cause for the error and, if so, where should I connect it?

[moralesvicente]

Hello clancymart, 

Thank you for reaching out to the Google Nest Community Forum. I understand that you're getting an error code (E294) on your Nest Thermostat after replacing the old one. Additionally, you may wonder if a fifth blue wire could be the cause of this error and where to connect it. No worries; I’m happy to help.

The E294 error code indicates that a required R wire isn't detected. This wire provides power to the thermostat; therefore, you need to reset your thermostat to its factory default settings and re-add it to the Google Home app. To address the trouble, follow the next steps:

• Turn off the power to your system at the breaker box, fuse box, or system switch. This helps prevent damage to your system and keeps you safe before manipulating the wires.
• Ensure that the wires are seated in the correct terminals and properly connected.
• On the Google Home app, remove the thermostat. To do this, tap and hold your device’s tile, select Settings, then tap Remove device > Remove.
• On your Nest Thermostat, perform a factory reset. For more details, refer to this article: Restart or reset a Nest thermostat.
• Finally, set up the device again, following the instructions in this article: Install your Nest thermostat.

Also, could you please confirm where the blue wire is connected to the HVAC control board so I can provide accurate information about it? If possible, share a picture with me.

Let me know how it goes.

Best regards,

Daniel