honeywell therm. heater/furnace stopped working (easy fix)[flame sensor]

The article lists common causes and step-by-step fixes for a Honeywell thermostat heat not working on Auto, including low battery, software/configuration issues, wiring, furnace or sensor faults, and blower problems. Recommended actions include restarting/resetting the thermostat, checking wiring and auto/heat settings, programming schedules, updating or resetting firmware, inspecting the furnace limit control, replacing a faulty sensor, cleaning filters/igniter, and calling an HVAC professional or support if needed.