Lennox Furnace Code E273
Soft lockout
Soft lockout. The furnace used up its maximum number of recycles and the last one was caused by flame failure, meaning the burner lit but the flame was lost.
Manual wording: “Soft lockout - Exceeded maximum number of recycles. Last recycle due to flame failure.”
Documented for: EL296UHE and SLP98UHV series
Likely causes, most common first
- Dirty flame sensor unable to hold the flame signal
- Poor unit ground lowering flame current
- Low or unstable gas pressure
- Vent or condensate restriction cutting the cycle short
What you can safely check yourself
- Check that other gas appliances in the house are working
- Check the outdoor intake and exhaust pipes for snow, ice or debris
- Turn the furnace power switch off for 30 seconds and back on once, one time only
When to call a technician
The manual's action is to measure flame sensor current, clean or replace the sensor and verify the unit ground. That is a technician job.
A Lennox furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- 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
- 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