Troubleshooting Common Nest Thermostat Error Codes


Updated: Jan 9, 2024

Explore our in-depth guide on resolving common Nest thermostat error codes, brought to you by Air Houston Mechanical LLC. We understand the importance of a seamlessly functioning thermostat in maintaining a comfortable home environment. Let’s dive into the troubleshooting steps for these smart devices.

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e298 – Critical

Exclusive to new Nest thermostat models, the e298 error code signals a power detachment from the system. The thermostat switches to the backup battery system, displaying the error until the issue is resolved.

  • Disconnected or damaged wiring.
  • Issues further along in the electrical system (circuit breaker, fuse box, or system switch).
  • Technician inspection required for identification and resolution.

e294 – Critical

Critical error code e294 appears when your Nest thermostat’s wiring needs reconfiguration, specifically the R wire. A factory reset may be performed first, followed by checking the wiring diagram and connectors. The technician will ensure each wire is properly placed into the connector, replacing any malfunctioning connectors.

e195 – Critical

This critical error code may appear during extremely hot weather, causing the HVAC system to break down. The thermostat’s backup battery drains, eventually powering down. Before calling a professional technician, you can attempt to supply power using a USB cable to troubleshoot the issue.

e103 – Critical

Another critical error code, e103, indicates an electrical error with your Nest thermostat, specifically an overcurrent problem. A technician will meticulously investigate the Nest’s electrical system to determine where the power surge is occurring.


Although not critical, error code n260 may still hinder normal thermostat usage. It pertains to the lack of a C wire or Nest Power Connector. You can inspect the C connector for a C wire and modify the wiring. Installation of a Nest Power Connector may trigger error code E297, which can be resolved by updating the thermostat in Settings -> Software -> Update.

e104 – Critical

Similar to error code e103, e104 is a critical error stemming from an overcurrent. It’s crucial to shut off power immediately to prevent electrical damage. Professional technicians can identify and resolve electrical damage.

e73 – Critical

When error code e73 appears, it indicates that the Rc wire is not receiving power. After visually checking the wires for any loose or damaged connections, contacting Air Houston Mechanical LLC for professional assistance is recommended.

Contact Air Houston Mechanical LLC for Expert Assistance!

While this guide provides valuable insights, contacting Air Houston Mechanical LLC for professional assistance ensures a swift resolution to your thermostat issues. Our friendly professionals are ready to help you restore your thermostat to full working order.

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