Nest Nest Learning Thermostat (3rd Gen) C01 Error Fix: Cannot Connect to Wi-Fi Network

Error code C01 on the Nest Nest Learning Thermostat (3rd Gen) means: Cannot Connect to Wi-Fi Network. Thermostat cannot find or connect to the home Wi-Fi network. Network may appear in the scan but connection fails. Common causes: incorrect Wi-Fi password, network is 5GHz only (Learning 3rd Gen and Thermostat E only support 2.4GHz), WPA3-only security (Nest requires WPA2), router MAC filtering blocking the thermostat, or the thermostat is too far from the router. Check Wi-Fi signal strength in Settings > Technical Info — RSSI should be between -30 and -60 dBm. Below -70 dBm is weak.

The most successful fix is "Reset Thermostat Network Settings and Update Router Security" (medium difficulty, ~30 minutes). This fix costs nothing. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Reset Thermostat Network Settings and Update Router Security") is rated medium difficulty and takes about 30 minutes. Tools needed: Smartphone or computer to access router settings.

DIY cost: $0. Professional repair typically costs $100-$150. Many homeowners save money by trying the top-ranked community fix first.

The Nest Nest Learning Thermostat (3rd Gen) has 8 other known error codes, including: A01 (No Power / Low Battery), A02 ('Delayed' Message on Display), A03 (No Power to Rh/Rc Wire), A04 (W1/W2 Heating Wire Not Detected), A05 (Y1/Y2 Cooling Wire Not Detected), and 3 more.

Error code C01 also appears on 3 other Nest models: Nest Learning Thermostat (4th Gen), Nest Thermostat (2020), Nest Thermostat E. The fix may vary by model, so check each model's specific page for tailored repair steps.