Lennox Furnace Code E111
Warning
Line voltage polarity reversed. Hot and neutral are swapped in the 120-volt supply to the furnace.
Manual wording: “Line voltage polarity reversed. Reverse line power voltage wiring. System resumes normal operation 5 seconds after fault recovered.”
Documented for: EL296UHE series
Likely causes, most common first
- Hot and neutral reversed at the furnace junction box
- Reversed polarity in the branch circuit feeding the furnace
What you can safely check yourself
- Check that the furnace disconnect switch and breaker are on
- Turn the furnace power switch off for 30 seconds and back on once
When to call a technician
Reversing the line power wiring back to correct polarity is work inside the junction box. Call a licensed electrician or HVAC technician.
A Lennox furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- 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