⚠
warning Honeywell
Error Code 188
Replace UV bulb (1) — a UV bulb needs to be replaced.
? What Causes This
UV bulb has reached the end of its operational life.
✓ How to Fix It
Replace the UV bulb or contact your heating or cooling professional. Reset the timer by touching Dismiss on the thermostat screen after replacement.
Source: page 28 of the official manual
From the manual
