HVAC Code Lookup

Lennox Furnace Code E223

Warning

The low pressure switch failed to close when it should have. The control cannot prove that the combustion air inducer is producing enough draft to safely light the burners.

Manual wording: “Low pressure switch failed open. Check pressure (inches w.c.) of low pressure switch closing on heat call. Inspect vent and combustion air inducer for correct operation and restriction.”

Documented for: EL296UHE and SLP98UHV series

Likely causes, most common first

  1. Blocked or restricted intake or exhaust vent pipe
  2. Plugged condensate drain or trap backing water into the system
  3. Cracked, kinked or disconnected pressure switch hose
  4. Weak or failing combustion air inducer

What you can safely check yourself

  • Check the outdoor intake and exhaust pipes for snow, ice, leaves or nesting debris
  • Check the condensate drain line and trap for a clog or standing water
  • Check that the furnace door is fully seated
  • Turn the furnace power switch off for 30 seconds and back on once

When to call a technician

The manual's action is to measure pressure switch closing pressure in inches of water column and inspect the vent and combustion air inducer for restriction. That needs a manometer and an open cabinet. Never jumper a pressure switch.

A Lennox furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Lennox codes