Lennox EL296UHV Error Code E 275: Soft Lockout - Flame Out of Sequence
What Does Code E 275 Mean?
Error code E 275 on the Lennox EL296UHV is a flame-out-of-sequence soft lockout. The SureLight integrated control detected flame current at a point in the cycle when there should be no flame, and then that signal disappeared. Because sensing flame when the gas valve is supposed to be closed is a potential safety concern, the control does not just briefly retry — it enters a 1-hour soft lockout, holding the furnace off for about an hour before it will attempt to prove a stable flame again.
The most concerning cause is a gas valve that is leaking a small amount of gas past its seat. Gas seeping through can ignite from residual heat in the burner area, register on the flame sensor, then burn off, which produces exactly the appear-then-disappear signal this code describes. Because of that possibility, the control's own guidance is to shut off the gas and check the valve for leakage before returning the furnace to service. This is a technician task, not a homeowner adjustment.
E 275 is the escalated, lockout form of the same condition flagged by E 241 (flame sensed out of sequence). E 241 is the detection of unexpected flame; E 275 is the 1-hour soft lockout the control enters when that condition warrants shutting the furnace down for an extended period so any leaked gas can clear. If you smell gas, do not wait for the code to clear — leave the home and call your gas company from outside.
What You'll Notice
- The furnace is locked out and will not attempt to run for roughly an hour
- The seven-segment LED shows E 275 (and sometimes E 241 in the history)
- You may notice a brief whiff of gas or an unexpected short flame at the burners
- The furnace shut down on its own outside of a normal heat call
- Heating is interrupted for about an hour at a time before the furnace retries
How This Is Diagnosed
Because E 275 can indicate gas escaping past a closed valve, a technician's first action is to shut off the gas supply and check the gas valve for leakage, confirming it seals fully when de-energized. They also verify the flame sensor is not reading a false or residual signal and that wiring to the valve and sensor is correct.
Only after the valve is confirmed to hold and no unexpected flame is present would the furnace be returned to service, at which point the control requires a stable, properly sequenced flame before it clears the lockout.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The furnace keeps entering a 1-hour lockout with E 275
- You smell gas near the furnace — leave the home first and call your gas company from outside
- E 241 and E 275 both appear in the error history
- You see or hear an unexpected flame or ignition when the furnace should be off
- The furnace shuts itself down when there is no call for heat
Frequently Asked Questions
Why does the furnace stay off for a full hour?
E 275 is a 1-hour soft lockout because sensing flame out of sequence can involve gas where there should be none. The extended hold gives any leaked gas time to dissipate before the furnace attempts to run again.
How is E 275 related to E 241?
E 241 is the control detecting flame out of sequence. E 275 is the 1-hour soft lockout the control escalates to when that condition warrants shutting down for an extended period. Seeing both together points to the same underlying issue.
Is this dangerous?
It can be, because one cause is a gas valve leaking past its seat, so it should be checked promptly by a technician. If you smell gas at any point, leave the home and call your gas company from outside rather than waiting for the lockout to clear.
✓ Verified against manufacturer service manual — March 2026