Error Code E 275
High

Lennox EL296UHV Error Code E 275: Soft Lockout - Flame Out of Sequence

TL;DR
Your Lennox EL296UHV has entered a 1-hour lockout after detecting flame at an unexpected time. This may indicate a gas valve leak.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code E 275 Mean?

Error code E275 on the Lennox EL296UHV indicates a soft lockout triggered by flame being sensed out of sequence. The control board detected a flame signal when no flame should have been present, and then the flame signal disappeared. The furnace enters a 1-hour safety lockout as a precaution.

This is the lockout escalation of E241 (flame sensed out of sequence). Where E241 is the initial detection of unexpected flame, E275 is the resulting lockout after the system determined the condition was serious enough to shut down for an extended period. The 1-hour lockout gives any leaked gas time to dissipate and prevents the furnace from cycling on a potentially unsafe gas valve.

The most concerning cause is a gas valve that is leaking a small amount of gas past its seat. The leaked gas ignites from residual heat, triggers the flame sensor, and then burns off — causing the flame to appear and disappear. The lockout clears only when flame stability has been proven. A technician must inspect the gas valve for leaks before the furnace should be returned to service.

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Lennox EL296UHV Unit Information (Corp. 1125-L5)

✓ Verified against manufacturer service manual — March 2026