Lennox EL296UHV Error Code E 270: Soft Lockout - Ignition Failure
What Does Code E 270 Mean?
Error code E 270 on the Lennox EL296UHV is a soft lockout for ignition failure: the SureLight integrated control tried to light the burners, purged, and retried the maximum number of times, and on none of those attempts did it read flame current. Because it is a soft lockout rather than a hard lockout, the control does not require anyone to cut and restore power to recover. It simply stops trying, then clears the code on its own the next time a heat call runs to completion. If the underlying fault is still present, it will run through its retries again and relock.
The name is a little misleading on this model. The burners may actually be lighting on each attempt while the flame sensor fails to prove the flame, which is why the single most common cause of E 270 is a marginal or fouled flame sensor rather than a furnace that never lit. That is the key difference from E 273, the flame-failure soft lockout: with E 273 the EL296UHV proved a good flame and then lost it partway through the run, while with E 270 it never registered flame current across any of its ignition retries.
The second common cause is a failed hot surface ignitor that no longer gets hot enough to light the gas. When the ignitor circuit itself is at fault the SureLight control may instead post E 290 (ignitor circuit fault) or E 207 (hot surface ignitor sensed open). A related low-flame-current condition can also surface as E 240. Less often, E 270 is a gas-supply problem: a closed manual valve, a tripped upstream safety, or low supply pressure that keeps the burners from lighting.
What You'll Notice
- No heat, and the seven-segment LED on the control shows E 270
- You hear the inducer spin up and the furnace attempt to light several times in a row, then everything goes quiet
- The burners may flash on briefly and drop out, or never appear to light at all
- The furnace stops retrying and waits until the next thermostat heat call before trying again
- The home keeps cooling down even though the thermostat is calling for heat
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Dirty or failed flame sensor | Most common | ✗ Call a pro → |
| Failed hot surface ignitor | Common | ✗ Call a pro → |
How This Is Diagnosed
A technician generally works from the most common cause outward. They first read the flame-sensor microamp signal through the control's diagnostics and inspect the sensor rod, since a fouled sensor that cannot prove a real flame is the leading cause of E 270. If the flame signal checks out, they confirm the hot surface ignitor actually glows and lights the burners, and measure its resistance to rule out a failing ignitor.
If ignition itself is fine, attention moves to gas delivery: that the manual gas valve is open, that supply and manifold pressure are within spec, and that no upstream safety has tripped. The technician also checks the unit ground, because a poor ground can leave the control unable to read an otherwise healthy flame.
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:
- E 270 returns on every heat call and the house is steadily losing temperature
- You can see the burners light but the furnace still locks out
- The furnace also logs E 240 (low flame current) or E 290 (ignitor circuit fault)
- The code first appeared after a gas outage, meter work, or a nearby appliance losing gas
- You smell gas near the furnace — in that case leave the home and call your gas company from outside
Frequently Asked Questions
Why does it say ignition failure when I saw the burners light?
E 270 is triggered by the absence of flame current, not by whether gas ignited. A dirty or weak flame sensor can fail to prove a flame that is actually burning, so the control counts the attempt as a failure even though you saw fire.
Will the furnace clear this code by itself?
Yes. As a soft lockout, E 270 clears once a heat call finishes successfully. But if the sensor, ignitor, or gas issue is still there, the furnace will just run through its retries and lock out again.
Is it harmful to keep cycling power to force another attempt?
The soft lockout already retries on its own, so power-cycling mainly sends more unproven ignition attempts without fixing the root cause. It is better to have the flame sensor, ignitor, and gas supply checked than to keep forcing restarts.
✓ Verified against manufacturer service manual — March 2026