Furnace / HVAC
Lennox furnace error codes
Every Lennox furnace code in our database, with plain-English meanings, likely causes, and what to try before calling for service. Codes can vary by model and year — always confirm against the legend on your unit or its manual.
- 3 blinks Pressure switch failed to close
- 4 blinks Limit switch open (overheating)
- 5 blinks Flame rollout switch open safety
- 6 blinks Soft lockout — repeated ignition or flame-sensing failure
- 7 blinks Low flame signal
- E200 Rollout limit switch open safety
- E201 Lost communication with blower motor
- E223 Low-pressure switch open
- E241 Flame sensed out of sequence safety