What does Lennox code 273 mean?
Lennox furnace code 273 means the furnace exceeded its recycle limit after losing the flame signal on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Lennox code 273?
- A dirty or weak flame sensor
- Unstable gas pressure or burner flame
- Poor grounding or flame-sensor wiring
Can I troubleshoot Lennox code 273?
- Confirm the gas shutoff has not been moved and the furnace panel is fully seated.
- Try one reset and watch whether the burners light and then shut off again.
How much does Lennox code 273 cost to fix?
A flame sensor cleaning or replacement typically costs between $100 and $600 nationally.
When should I call a technician?
Call a technician if flame drops out again or ignition becomes delayed or noisy.
Sources and model scope
Fault codes vary by model and control board. Confirm the diagnostic chart inside your furnace panel or the official manual before acting.
Scope used here: Lennox integrated controls covered by installation instructions 508001-02D.
- Lennox Industries: Installation Instructions — Integrated Control Diagnostic Codes
508001-02D · Lennox furnaces explicitly covered by installation instructions 508001-02D; not a universal Lennox code list.
Compiled by Warmlo Editorial · Reviewed August 2026
This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.