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Error code reference

Lennox Furnace Error Code E265

Soft lockout

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What the E265 error code actually means

Your Lennox furnace detected a flame at the wrong point in its startup process, then that flame signal disappeared, which caused the furnace to pause and lock out temporarily. This is a secondary error that follows an earlier fault, so the furnace is telling you something went wrong with how or when the burner flame appeared. The furnace may restart on its own, but the underlying issue needs to be diagnosed to prevent it from happening again.

Diagnostic procedure

The full E265 procedure

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First diagnostic step
See E241.
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Most common causes of E265

Ranked by how often they cause this code
  1. 1Faulty or leaking gas valve
  2. 2Contaminated or failed flame sensor
  3. 3Control board fault
  4. 4Ignition system issue causing delayed or abnormal flame establishment
  5. 5Wiring or connection problem at the flame sensor circuit

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Questions people ask about E265

What does E265 mean on a Lennox furnace?
E265 is a soft lockout code indicating that the furnace detected a flame signal out of sequence during its operation, which is rooted in an E241 fault, and that flame signal subsequently disappeared. The furnace enters a temporary lockout as a safety response. Because E265 is a secondary code, diagnosing it requires investigating the E241 fault condition directly.
Is it safe to keep running my furnace with an E265 code?
E265 is a soft lockout with automatic restart capability, but the underlying E241 fault involves out-of-sequence flame detection, which is a condition the safety controls are specifically designed to catch. You should not continue operating the furnace while repeatedly seeing this code without having it properly diagnosed, as uncontrolled flame presence can be a safety concern.
How much will it cost to repair a Lennox furnace showing E265?
Repair costs depend on which component is at fault. Flame sensor cleaning or replacement is typically the least expensive repair, often in the range of $75 to $200 including labor. A gas valve replacement can run from $250 to $600 or more depending on the model and labor rates. Control board replacement is generally the most costly repair, often ranging from $350 to $700 or higher.
Can I fix E265 myself, or do I need a technician?
Some contributing issues, such as a dirty flame sensor, can be cleaned by a knowledgeable DIYer who is comfortable working on furnace components. However, problems involving the gas valve or control board require a qualified HVAC technician. Since E265 involves gas valve operation and flame sequencing, professional diagnosis is strongly recommended if the fault recurs after cleaning the flame sensor.
Will resetting the furnace clear the E265 code?
Because E265 is a soft lockout, the furnace will attempt to restart automatically without a manual reset. However, resetting or restarting the furnace will not resolve the root cause tied to the E241 fault. If the underlying problem is not corrected, the fault sequence will repeat and the code will return.

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