Completed furnace, maintenance and inspection. I checked amp draws and components. I tested air pressure and temp splits. I cleaned flame sensor, spark igniter, and furnace. Wire head to the flame sensor was not connected properly so when I touched the wire to pull out the flame sensor, the wire fell away from the flame sensor. I installed a new wire head onto the wire so the flame sensor is connected properly now. I helped customer get logged into the smart AC app. Furnace is running within manufacture specifications at departure.