Previously working thermostat gen 4 throwing "e-299" "c wire broken"

[papatpk]

Previously working thermostat throwing "e-299" "c wire broken" Unit working flawlessly for 9 months.  Quick power outage prior to fault.

[papatpk]

Has anyone seen this before and what could be the issue?

[Derickf]

Hi @papatpk,

Thanks for reaching out to the community. I'm sorry to hear that your Nest Thermostat is showing an “E-299” error code after a power outage. I’m happy to assist.

Based on the error code you are getting from your thermostat, it is necessary to perform some troubleshooting steps in the thermostat’s baseplate. For more information, please visit our Contact Us page and follow the prompts until you reach Contact Options. Then select “Get a Call” or “Chat.” 

Please keep me posted if you have any other questions.

Best regards.

Derick.