Lennox Error Code 114 — What It Means
Lennox error code 114 indicates an ignition failure lockout — the furnace attempted to ignite the burner but the flame sensor did not detect a flame within the trial-for-ignition period. After a set number of failed ignition attempts (typically 3 retries), the furnace locks out on code 114. This appears on Lennox G61MP, XC17, and other models with a digital control board display. The furnace will not attempt ignition again until manually reset. Code 114 is one of the most common Lennox service calls.
Common Causes
- Failed hot surface igniter (HSI) — The silicon carbide or silicon nitride igniter has cracked or worn to the point where it no longer reaches ignition temperature (approximately 1800°F). This is the most common hardware cause of code 114.
- Dirty or failed flame sensor — Even if ignition occurs, a coated or corroded flame sensor rod won’t detect the flame and the gas valve closes, causing code 114 to log.
- No gas supply or low gas pressure — A closed shutoff valve, low supply pressure, or a gas valve that fails to open prevents combustion from occurring.
- Draft/pressure switch fault preventing gas valve opening — If the pressure switch hasn’t confirmed adequate draft before the ignition trial, the gas valve won’t open and code 114 results.
Step-by-Step Fix {#fix}
- Visually inspect the igniter — Power off the furnace and locate the hot surface igniter (a fragile ceramic element in the burner assembly). Look for cracks, a broken element, or discoloration from a prior failure. Handle only by the lead wires — never touch the ceramic.
- Test the igniter electrically — With the furnace off, disconnect the igniter leads and measure resistance across them. A healthy Lennox igniter reads 40–90 ohms. Open circuit (OL) = failed igniter requiring replacement.
- Clean the flame sensor — Remove the flame sensor rod (one screw) and lightly clean the rod with fine emery cloth to remove carbon buildup. Reinstall and test.
- Confirm gas supply — Verify the gas shutoff valve at the furnace is fully open and other gas appliances in the home are working. Listen for the gas valve click during an ignition attempt.
- Reset and observe — Press the furnace’s manual reset button (or cycle the breaker) and initiate a heat call. Watch and listen: igniter should glow orange/red within 15–30 seconds, then the gas valve opens and the burner lights. If gas lights but shuts off quickly, clean the flame sensor.
Parts Often Needed
| Part | Notes |
|---|---|
| Hot surface igniter (HSI) | Amazon | Confirm OEM part number; Lennox igniter resistance spec is 40–90 ohms |
| Flame sensor | Amazon | Replace if cleaning doesn’t restore reliable flame detection |
| Gas valve | Amazon | Replace only after confirming gas supply is adequate and ignition is working |
When to Call a Pro
If the igniter glows, gas is confirmed, and code 114 persists after cleaning the flame sensor, the gas valve’s opening pressure or the pressure switch may require adjustment — tasks that require a licensed HVAC technician with gas certification.
See Also
- Lennox Error Code 411 — Ignition Proving Fault Fix
- Lennox Error Code 412 — Limit Switch Fault Fix
- Lennox Error Code 540 — Communicating System Fault (Detailed Guide)
- Lennox Mini Split Error Code E1 — Causes & Fix