When I arrived, the furnace was running. I logged into the system and found that the furnace had been failing at ignition. This was causing the furnace to go into a one hour lockout. When the lockout ended, the furnace would try to start up again and fail ignition and go back into a lockout. I cleaned the flame sensor. I also pulled the burner box out of the furnace and cleaned the burners as well as the spark igniter. I reinstalled the parts and made system restart multiple times. Furnace started up without any issues. Furnace is operational at departure.