Reading Error Codes
Most modern furnaces use LED flash codes to indicate problems. Count the flashes and refer to the code chart on the furnace door.
Common Error Codes
- 1 flash: Normal operation
- 2 flashes: External lockout
- 3 flashes: Pressure switch error
- 4 flashes: Open high limit switch
- 5 flashes: Flame sensed without gas valve
- 6 flashes: Ignition failure
- 7 flashes: Rollout switch open
Resetting the Board
- Turn off power for 30 seconds
- Restore power and observe LED
- If code persists, address the underlying issue