HVAC Code Lookup

Lennox Furnace Code E225

Warning

The high pressure switch failed to close. On a two-stage or variable-capacity furnace this switch has to close before the unit can fire on high fire.

Manual wording: “High pressure switch failed open. Check pressure (inches w.c.) of high 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
  3. Cracked, kinked or disconnected high pressure switch hose
  4. Combustion air inducer not reaching full speed

What you can safely check yourself

  • Check the outdoor intake and exhaust pipes for snow, ice or debris
  • Check the condensate drain line and trap for a clog
  • Turn the furnace power switch off for 30 seconds and back on once

When to call a technician

Measuring switch closing pressure and inspecting the inducer for restriction requires a manometer and an open cabinet. Have a technician do it.

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

Sources

Other Lennox codes