Thermostat display shows E01 and cannot connect to home Wi‑Fi network

Safety first: This issue is usually low‑voltage (24V) and low risk, but always turn off power to the HVAC system at the breaker before removing the thermostat from the wall plate.

• Step 1 – Basic network reset:
  • On the Gosund thermostat, go to Settings > Wi‑Fi and select Forget Network.
  • Reboot your router and wait 2–3 minutes until Wi‑Fi is fully up.
  • On the thermostat, search for networks and connect to a 2.4GHz SSID (Gosund thermostats typically do not support 5GHz).
• Step 2 – Check router settings:
  • Disable MAC filtering or add the thermostat’s MAC address to the allowed list.
  • Ensure WPA2‑PSK (AES) security is enabled; avoid WPA3‑only or enterprise modes.
  • Ensure the router is not set to “802.11n‑only”; allow mixed b/g/n on 2.4GHz.
• Step 3 – Power cycle and reset thermostat network:
  • Turn off HVAC power at the breaker for 30 seconds, then restore power.
  • On the thermostat, perform a network reset (see Gosund app or manual; usually under System > Reset > Network).
• Step 4 – Inspect Wi‑Fi antenna and PCB (advanced):
  • Turn off power at the breaker.
  • Remove the thermostat from the wall plate and inspect the small Wi‑Fi antenna lead or PCB trace for damage or disconnection.
  • If the antenna is broken or the Wi‑Fi module on the main control board is visibly damaged, replacement of the main control PCB is required.
• When to call a pro: If E01 persists after resets and router checks, the Wi‑Fi module on the main board is likely defective and the thermostat should be replaced or serviced by the manufacturer.