E13 displayed and thermostat schedules or settings keep resetting unexpectedly

Safety: No high‑voltage work is required for this issue.

• Step 1 – Stable power:
  • Ensure the thermostat has a solid C‑wire connection and is not losing power intermittently.
  • Check for frequent breaker trips or furnace power cycling.
• Step 2 – Factory reset:
  • Perform a full factory reset from the settings menu.
  • Reconfigure Wi‑Fi, schedules, and preferences from scratch.
• Step 3 – Firmware update:
  • Use the Gosund app to check for and install any available firmware updates.
• Step 4 – Monitor behavior:
  • If E13 reappears and settings continue to be lost, the internal memory chip is likely failing.
• Step 5 – Replace thermostat:
  • EEPROM/flash components are not field‑replaceable; replace the thermostat.