⚠
warning Honeywell
Error Code 388
Register online for remote access and outdoor temperature — registration is required for full thermostat functionality.
? What Causes This
Thermostat is not registered with Resideo online service.
✓ How to Fix It
Download the Resideo App and register your thermostat for remote access and outdoor temperature information.
Source: page 28 of the official manual
From the manual
