Understanding LED flash patterns and error codes on Lennox furnaces
Count the LED flashes on your furnace control board to identify the error
What it means:
System attempted to ignite but failed. Could indicate gas valve, igniter, or flame sensor issues.
What to do:
Check gas supply is on. If problem persists, professional service needed.
What it means:
Pressure switch not closing properly. Could be blocked venting or faulty switch.
What to do:
Check for blocked vents or exhaust pipes. Contact technician if issue continues.
What it means:
Pressure switch stuck in closed position when it should be open.
What to do:
Requires professional diagnosis and repair.
What it means:
System overheating. Could be restricted airflow or dirty filter.
What to do:
Check and replace air filter. Ensure all vents are open. Call if problem persists.
What it means:
Safety limit triggered due to improper venting or burner issues.
What to do:
Do not reset repeatedly. This is a safety concern — call immediately.
What it means:
Multiple failed ignition attempts have locked the system.
What to do:
Turn system off for 5 minutes, then try restart. If lockout repeats, call technician.
Our technicians are experienced with all Lennox furnace models and error codes. We carry common parts for same-day repairs.
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