Lennox E270 Error Code: Lockout: flame failure on ignition
Updated October 2026 · Sourced from Lennox documentation
Soft lockout. The furnace exceeded its ignition retries and the last failed retry was due to flame failure. The lockout lasts 60 minutes.
Is it safe to keep running? Check the steps below first. Call a licensed HVAC technician if the furnace does not light after a reset. Igniter, flame sensor and gas valve checks are for a professional.
E270 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| E270 Shown as an E code on the 7-segment display of the integrated control | Lockout: flame failure on ignition | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) |
Check this first
Only steps a homeowner can do safely. Do not open electrical panels or the burner area.
- Make sure the manual gas valve to the furnace is on (handle in line with the pipe), following the lighting instructions on the furnace label.
- Turn the furnace power switch or breaker off for 30 seconds, then back on, and see if the code clears.
- Check the thermostat is set to Heat, set above room temperature, and has fresh batteries if it uses them.
- Look outside at the furnace vent and intake pipes for snow, leaves, nests or other blockage, and clear anything you can reach safely.
🛑 Stop and call a licensed pro if
- Call a licensed HVAC technician if the furnace does not light after a reset. Igniter, flame sensor and gas valve checks are for a professional.
- You smell gas. Leave the house, do not touch switches, and call your gas utility from outside.
- Flame rollout, limit or pressure switch codes that come back after one reset.
- Anything involving the control board, gas valve, flame sensor, igniter or venting.
- A carbon monoxide alarm sounds. Get everyone outside and call 911 or the fire department.
Safe first steps for any Lennox code
- Count the LED flashes through the blower door window before you switch anything off. Cutting power can clear the code.
- Replace or clean the furnace air filter.
- Check the thermostat: correct mode, set above room temperature, and fresh batteries.
- Make sure the furnace power switch and breaker are on. If the furnace has locked out, turning the power off and back on once restarts it.
- Make sure the gas valve is in the ON position, following the lighting instructions on the furnace label only.
- On high-efficiency furnaces, look at the outside vent and intake pipes for snow, ice, leaves or nests (look only, do not take pipes apart).
Source: Lennox SL280UHVK Installation Instructions 508553-01 (01/2025), Ignition Control Diagnostic Codes (continued), p.37. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
Shaun Cain · Certified HVAC & Refrigeration Technician · Ask an HVAC technician