Lennox SLP98UHV Error Code E 275: Soft Lockout - Flame Out of Sequence
What Does Code E 275 Mean?
The E 275 fault on the Lennox SLP98UHV is a soft lockout that follows an E 241 fault (flame sensed out of sequence) which has since cleared. In other words, the furnace earlier detected a flame signal at a time when the gas valve should have been closed, that signal has now gone away on its own, and the SureLight control holds the furnace in a lockout as a safety precaution rather than simply resuming.
The original E 241 condition means flame was present when it should not have been — most often because the gas valve leaked through or briefly stuck open before reseating. Even though the flame signal has cleared and the furnace may look like it wants to run normally, the fact that it happened at all suggests the gas valve may not be sealing reliably. E 275 exists so the furnace does not quietly return to service after such an event without being checked.
Because the trigger is a possible intermittent gas valve leak, E 275 should be taken as seriously as the E 241 that preceded it. A technician needs to inspect and leak-test the gas valve, look for any sign of gas escaping, and verify the flame-sensing circuit to rule out a false reading. The furnace should stay off until that inspection is done.
What You'll Notice
- The furnace is locked out and displays E 275, often just after an E 241
- The unit will not resume heating even though it now seems otherwise normal
- A gas smell may have been noticed near the furnace earlier
- The furnace ran erratically or shut down unexpectedly before the lockout
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Previous gas valve leak condition (E 241) that has since cleared | Most common | ✗ Call a pro → |
How This Is Diagnosed
Because E 275 stems from an out-of-sequence flame event, a technician's priority is the gas side: leak-testing and inspecting the gas valve to confirm it seats fully and does not bleed through, and replacing it if it does not. They also confirm there is no active gas leak around the burner and valve.
After the gas valve is verified sound, they check the flame sensor and its wiring for shorts or moisture that could have produced a false flame signal, then test-fire the furnace and confirm the flame goes out cleanly when commanded before returning it to service.
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:
- This code follows a possible gas valve leak and needs professional inspection before the furnace runs again
- You smell gas near the furnace at any point — treat it as an emergency and shut off the gas supply
- The code appeared even though the furnace now seems to run normally
- The furnace is locked out on E 275, or it was preceded by an E 241
Frequently Asked Questions
The furnace seems fine now — can I just clear E 275 and use it?
No. E 275 follows an out-of-sequence flame event that can indicate a gas valve leaking through, and that can recur even if things look normal now. The valve should be inspected and leak-tested by a technician before the furnace is put back in service.
What is the difference between E 241 and E 275?
E 241 is the live fault — flame is being sensed when it shouldn't be. E 275 is the soft lockout that follows once that flame signal has cleared, holding the furnace off as a precaution. Both point back to the same possible gas valve leak that needs professional inspection.
✓ Verified against manufacturer service manual — March 2026