Nest thermostat displays E3 and cannot detect the outdoor temperature or weather data

Note: This is not a high‑voltage issue. You can troubleshoot without powering down HVAC equipment.

• Check internet: Confirm other devices on the same network can access the internet. If not, reboot the modem/router.
• Verify Nest service: Check Nest/Google Home service status online from another device. If there is an outage, wait until service is restored.
• Location settings: In the Nest app, open your home, go to Settings > Home info and verify address and time zone. Incorrect location can cause weather data errors.
• Router/firewall: Ensure your router is not blocking outbound connections for the Nest thermostat. Disable any strict parental controls or firewall rules temporarily to test.
• Restart thermostat: Restart the Nest and re‑connect to Wi‑Fi. If E3 persists while internet and services are normal, the issue may be firmware‑related; perform a factory reset as a last resort (note: this clears schedules and settings).