01-25-2023 10:33 AM - edited 01-25-2023 10:33 AM
My Nest keeps disconnecting from Wifi and turning off because of M20 and E298 error messages. When I check the power information, it shows that voltage is fluctuating to the thermostat. However, when I use my multimeter to check the voltage to the thermostat it is steady at 24V. What gives? Is the thermostat defective?
02-01-2023 03:25 PM
Thanks for reaching out and for being a step ahead of us.
The reason why the Nest Thermostat gives you that code if the common wire isn't properly grounded or a connection failure may be in one of the power terminals and causes the power loss. Could you please share your thermostat wiring?
You can check out this guide.
02-06-2023 01:12 PM
Hi Jenelyn - thanks for following up. My house is older so it only has a R/W set up without a common wire. However, I'm confused why a common wire is required when the R/W is giving the thermostat 24V of consistent power per my multimeter. Is a common wire required irrespective?
02-07-2023 08:31 AM
Thanks for getting back to us, I'm sorry for the confusion. Unlike other wires connected to your Nest Thermostat, a C wire doesn’t control heating or cooling functions. It only provides constant power to your thermostat to make sure that your thermostat will avoid any power issues.
Instead of C wire you can install the Nest Power Connector as a substitute for C wire.
You can check this link for additional information about Common wire and Nest Power Connector.
02-10-2023 10:20 AM
@BEinDC I'm dropping by to ensure that everything is covered here. How's it going with your Nest Thermostat? Try giving these steps a try:
Looking forward to your response.
I appreciate the help, Jenelyn.
02-11-2023 02:52 PM
Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let us know.
02-05-2023 12:13 PM
I wanted to follow up and see if you still need help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.
02-06-2023 12:24 PM
I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.