What could be the cause of a Goodman furnace showing 4 flashes on the diagnostic code, and how can this issue be resolved?

A Goodman furnace showing 4 flashes on the diagnostic code may indicate an issue with the open high limit switch. This could be caused by overheating or a malfunction in the switch itself. To resolve this issue, you can try resetting the switch or replacing it if necessary. It is recommended to consult a professional HVAC technician for proper diagnosis and repair.