Lennox Furnace Code E224
Warning
The low pressure switch failed closed. The switch reads closed when the control expects it to be open, so the control cannot verify draft before lighting.
Manual wording: “Low pressure switch failed closed. Check low pressure switch for closed contacts, measure inches of water column of operating pressure, inspect vent and combustion air inducer for correct operation and restriction.”
Documented for: SLP98UHV and EL296UHE series
Likely causes, most common first
- Pressure switch stuck closed
- Pressure switch tubing misrouted or blocked
- Shorted pressure switch wiring
What you can safely check yourself
- Turn the furnace power switch off for 30 seconds and back on once
When to call a technician
A pressure switch stuck closed is a failed safety device. It has to be tested and replaced by a technician, never bypassed.
A Lennox furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- SLP98UHV Service Literature (Corp. 1029-L7), Table 14 - LED 7 Segment Status / Error Code and Integrated Control Diagnostic Codes (Lennox Industries Inc., SLP98UHV series variable-capacity communicating gas furnace (66,000-132,000 Btuh)) · checked 2026-08-25
- EL296UHE Service Literature (Corp. 1246-L10), Table 4 - Integrated Control Diagnostic Codes (Lennox Industries Inc., EL296UHE series 96% AFUE two-stage upflow/horizontal gas furnace (EL296UH045XE36B, EL296UH070XE36B, EL296UH090XE48C)) · checked 2026-08-25