Nest N262 error during extreme cold -- heating working ok, burning through batteries, wirring error?

[rcalinjageman]

We have a Nest thermostat that has been working fine for months, heating and cooling.

This weekend, during Chicago's annual polar vortex we started getting an n252 issue.  Changed the batteries - error went away for a short time, then came back.  Changed batteries again and also checked all 4 wires while the faceplate was off -- this did not clear the issue.  Heating continues to work fine but there is also a reported wiring issue for an *OB wire that we don't have.  Power test seems to go fine, and yet reported to be disconnected from power. 

Photos of each screen I'm seeing and power status and power test are here: https://photos.app.goo.gl/QDdi2QiiFyuhabDu8

Guessing/hoping this will resolve when we get back to normal temps but wanted to ask for advice/input to be sure.

[Patrick_Caezza]

@rcalinjageman 

You have an installation issue.

Can you post a picture of how you have the Nest wired?

Can you post a picture of the original thermostat's wiring?

Are you using the Nest Power Connector?

Can you post a picture of how you have it wired?

[rcalinjageman]

@Patrick_Caezza

Thanks for responding.

Here is a photo of the wiring from the thermostat that was in our house from 2007-2018, when we got our first Nest: https://photos.app.goo.gl/cHkVW3uYnsFTDdCh8

I replaced the traditional thermostat with a Nest Learning (2nd gen?) with this wiring: https://photos.app.goo.gl/hMNUqb38SvuJTwrm9

And then this fall I replaced our Nest Learning with a brand new Nest Thermostat (long story, many regrets) with a wiring plate.  Here's a photo of the wiring as it stands: https://photos.app.goo.gl/8u2MfCTQYhxRV9Hg6

While trouble-shooting on a couple of occasions I re-checked the seatings of the wires, including this morning just before making this post.  Tonight I fully removed each wire from the plate and then reseated, and then rebooted the Nest.  Even though it was showing the same issues when I initiated the reboot, on booting back up it is showing no warnings/issues at all (for now). 

Maybe there was a wiring issue and re-seating the wires did the trick?  Or maybe the reboot?  Or maybe the warmer weather (went up to 20F today, much better than the 0-7 range we've had for the past 3 days when these problems emerged)?  Or maybe some combination... strange. 

Power now shows: Vin: 29.871 V, lin: 385, PS: Y-385, YP-2... definately better than a 21.44V from this morning.  Fingers crossed this is resolved...

[JuanCH]

Hi rcalinjageman,

Thanks for the information you've provided. Based on the information, it seems like you have the Nest Thermostat (2020). I deeply appreciate all the workarounds already done to resolve this inconvenience with the error code N262 and the error for the wire undetected 'O/B,' which it isn't connected to on the thermostat.

In case the inconvenience persists, I’d suggest checking if your system requires maintenance or needs to replace the air filter. Furthermore, since you received a message about the Nest Power Connector, please ensure it is securely connected to the furnace control board.
For more information, you can refer to this article: Nest Power Connector.

If you need more assistance in the future, feel free to post again.

Best regards,
Juan