Lennox E223 & E227 — Low pressure switch open

What this error means

Both codes point at the low-fire draft pressure switch failing to prove: E223 = failed open (never closed), E227 = opened during ignition or run. Causes: blocked vent or combustion-air intake, a struggling inducer, or — very common on 90%+ condensing units in winter — frozen or clogged condensate. (Sibling code E224 is the switch stuck CLOSED.)

Symptoms

• No ignition, or shutdowns mid-cycle
• E223 or E227 on the display
• Seasonal pattern (cold snaps) on condensing furnaces

Try this first (safe DIY steps)

1. Check and clear the exterior vent and intake terminations
2. Check the condensate trap/drain for clogs or freezing
3. Power off 30 seconds and restore

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

Recurring with clear venting: pressure switch ($150–$400) or inducer ($400–$1,100 installed).