Goodman furnace 4 flashes: open high-limit circuit

What Does Error 4 flashes Mean?

Four flashes on a Goodman furnace control means the primary limit circuit is open. The limit is a temperature safety that trips when the air leaving the heat exchanger is too hot, so the fault points at restricted airflow or poor heat transfer rather than at a failed switch. Applies to: Goodman and Amana single-stage and two-stage gas furnaces with an integrated ignition control This meaning applies to Goodman and Amana gas furnaces whose control legend lists four flashes as an open limit or open high-limit circuit. Flash-code meanings differ between control boards, so read the label inside the furnace blower door for the exact model. Owner-safe checks: With the furnace off, replace a loaded filter with the correct clean size, arrow pointing toward the blower, and confirm supply and return grilles are open and unblocked. | Note whether the four-flash code clears with airflow restored and whether it returns on the first or second heating stage. Qualified technician: Measuring temperature rise and static pressure, inspecting the blower motor, capacitor and wheel, and testing or replacing the limit switch are technician tasks, and the limit must not be bypassed.