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Nest 3rd Generation Thermostat

JWH
Community Member

Nest thermostat disconnected from app and will not reconnect giving me M15 error. I’ve tried all the troubleshooting mentioned and nothing. WiFi is working fine. I’m at a loss. 

1 ACCEPTED SOLUTION

JWH
Community Member

I’ve followed all the M15 troubleshooting including factory reset. No changes. Battery levels have been fluctuating between 3.7-3.8.  WiFi will connect but always disconnects a few minutes later. I do not have a C wire. If you still think the Nest Power connector will solve the problem I’ll give it a try. 

Thanks for your help! 

View solution in original post

12 REPLIES 12

Ashepherdson
Silver Product Expert
Silver Product Expert

Would suggest you factory reset and start from scratch, there must be a setting that got stuck during setup that isn't letting you move ahead.  

JWH
Community Member

Performed several resets with no changes. I gave up and skipped the app function. Scrolling through the  settings I noticed it  said low battery under the Nest App setting. I think the battery needs replaced and the low voltage is causing it to dump the WiFi, therefore not connecting to the app. Looking into replacing the battery. 

Ashepherdson
Silver Product Expert
Silver Product Expert

It's possible, do you have a C wire?  Can you check the voltage of the thermostat, should be at about 3.89v for normal operation 

GarrettDS
Community Specialist
Community Specialist

Hey there,
Just wanted to jump in here to check to make sure that you saw the response from Ashepherdson. Shoutout and huge thank you to Ashepherdson for the help here. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Have a great day.
Garrett DS

JWH
Community Member

Battery voltage reading 3.78. Noticed thermostat keeps dropping WiFi.  I’ve restarted routers and now I’m at a loss as to the M15 code. Still unable to add thermostat to Nest app. Nest camera works fine. 🤷🏻‍♂️

Ashepherdson
Silver Product Expert
Silver Product Expert

So an M15 error usually means that there is a pairing or configuration error (https://support.google.com/googlenest/answer/9633749?hl=en#:~:text=This%20means%20you%20have%20succe...

And the way to fix it is by factor reset.  IF this is happening because Wifi is dropping due to low power, then I am going to go back to my original question, do you have a C wire in your setup?  I ask this because the voltage is a Little lower than normal, which could be causing the power dips and wifi cutouts.  IF you do not have a C wire, then the Nest Power Connector would be what I suggest, https://store.google.com/product/nest_power_connector?hl=en-GB

JWH
Community Member

I’ve followed all the M15 troubleshooting including factory reset. No changes. Battery levels have been fluctuating between 3.7-3.8.  WiFi will connect but always disconnects a few minutes later. I do not have a C wire. If you still think the Nest Power connector will solve the problem I’ll give it a try. 

Thanks for your help! 

View solution in original post

JWH
Community Member

Issue resolved. Thanks!

Ashepherdson
Silver Product Expert
Silver Product Expert

Can you confirm if you resolved the issue by installing the power adapter, or another way?

GarrettDS
Community Specialist
Community Specialist

Hey there,
Shoutout and huge thank you to Ashepherdson for the help here. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Have a great day.
Garrett DS

JWH
Community Member

No, it was a router issue   It had been inadvertently placed on a blocked list. 

GarrettDS
Community Specialist
Community Specialist

Hey folks,
It looks like we haven't heard back from the OP so I'm going to go ahead and lock the thread. If you have any further questions or concerns, feel free to create a new thread.

Have a great day,
Garrett DS