How to clear n260 when the C wire is present and working on the Nest Thermostat (mirror)

[bghill]

The wiring connections on my boiler are poor. It uses poorly designed screw terminals and one night my C-wire popped out of its spot. So the thermostat correctly showed error n260.

After I put the wire back in place, the error message wouldn't go away. I took out a volt meter and confirmed that the the mount for the thermostat was reading 24V across C and R. I tried removing the batteries for a bit. I tried removing the batteries and putting it into the mount. It gave a no power error. When I put the batteries back, it went back to n260. Now, I know it was getting power, because presence sensing was working and it only spends energy on that if it has power. So it uses presence sense to light up when I walk in the room to tell me it is sure it doesn't have power even though presence sense is working.

What worked?  With the batteries in, I ran my fingers across the wires on the back side of the thermostat. By connecting two of the leads, it triggered something in the unit and it changed its message. Once I put it back on the wall, the n260 message was gone and it was working. I hope this helps someone else.

[Markjosephp]

Hello bghill,

Thanks for reaching out to the Google Nest Community Forum. I'd love to know more about this.

Could you share a photo of how you installed your Nest Power Connector? Also, please take a look at the article with some troubleshooting steps about the message code you're getting from your thermostat and let us know if that helps.

Regards,

Mark

[EmersonB]

Hi everyone,

@bghill how's it going with your Nest Thermostat? We would appreciate it if you could share with us the information we're asking above. Also, were you able to perform the steps from the link that Mark has shared? We'd be glad to hear from you — We'd like to make sure everything is working.

I appreciate the help, Mark.

Thanks,
Emerson

[bghill]

I got it working. As I said, it was wired correctly. The common wire (C-wire) at the heater popped out. I re-secured that wire but the Nest refused to notice it. I could test with a volt meter that the correct voltage was in place on all wires. Even rebooting the thermostat didn't help.

I posted this purely in case someone else got into the same situation. The solution wasn't anything that would be in your manuals. Your manuals don't seem to presume the thermostat will get into a stuck state and maintain it after a reboot. The device must have some non-volatile memory installed to keep record of the last state it was in before losing all battery power. That is handy for remembering WiFi settings between battery failures but makes for problems like this one possible.

Again, running my fingers across the leads in the back of the thermostat seems to have shorted two leads just enough to get the thermostat out of the stuck state and it posted a new error about being without wall power (correct since I was holding the thermostat in my hand). Once I put it back on the wall, it went back to a working state.

Thank you,

Brandon

[Jake]

Hey there,

Thank you for sharing the information, and what had helped resolve your issue for others. I wanted to check in with you, and see if you had any further questions from here. Please let me know, as I will be locking the thread in 24 hours with the issue being resolved.

Best regards,

Jake