Error Code E 273
High

Lennox EL296UHV Error Code E 273: Soft Lockout - Flame Failure

TL;DR
Your Lennox EL296UHV entered soft lockout because the flame kept going out during operation. Clean the flame sensor rod with a Scotch-Brite pad to restore reliable flame detection.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code E 273 Mean?

Error code E273 on the Lennox EL296UHV indicates a soft lockout caused by exceeding the maximum number of recycles, with the last recycle due to flame failure. The furnace successfully lit but repeatedly lost the flame signal during operation. After too many flame-loss events, the control board entered a soft lockout.

Each time the flame sensor loses its signal, the gas valve closes for safety and the system attempts to relight. When this cycle repeats too many times, the control determines there is a persistent issue and enters lockout. The lockout clears when a subsequent heat call finishes successfully.

The most common cause is a dirty flame sensor that is marginally detecting the flame — it works well enough to start but cannot maintain a consistent reading. You may also see E240 (low flame current) appearing before or alongside E273. The sensor develops a layer of oxidation and combustion residue that insulates it from the flame. Less commonly, a poor unit ground or intermittent gas pressure can cause this code.

Common Causes

Cause Likelihood DIY?
Dirty flame sensor Most common ✗ Call a pro →

How to Fix It: Clean the Flame Sensor Rod

⚠ Safety First
Always turn off the furnace at the power switch or breaker and shut off the gas supply before beginning. Do not proceed if you smell gas — leave the area and call your gas company immediately.

What You'll Need

Steps

  1. Turn off electrical power and gas supply Turn off the furnace at the circuit breaker. Turn the gas shutoff valve to the OFF position (handle perpendicular to the pipe). Allow the furnace to cool if it was recently running.
  2. Locate the flame sensor Remove the furnace access panel. The flame sensor is a thin metal rod mounted near the burner assembly. It has a single wire connected to it and is held by one mounting screw.
  3. Remove the flame sensor Disconnect the wire from the flame sensor. Remove the single mounting screw holding the sensor bracket. Carefully pull the sensor out of the burner area.
  4. Clean the sensor rod Gently rub the metal rod with a Scotch-Brite pad until the surface is clean and shiny. Rotate the rod while cleaning to cover the entire circumference. Wipe with a clean dry cloth to remove any residue. Do not use steel wool, as it can leave metal fibers that cause problems.
  5. Reinstall the flame sensor Slide the sensor back into its mounting position and secure with the mounting screw. Reconnect the wire firmly. Ensure the rod extends properly into the burner flame path.
  6. Restore power and gas, then test Turn the gas supply valve to ON (handle parallel to the pipe) and flip the circuit breaker to ON. Cycling the power clears the lockout. Set your thermostat to call for heat and monitor through 2-3 complete heating cycles to confirm the flame holds steady.
How to Verify
The furnace should ignite and maintain the flame through multiple complete heating cycles without E273 or E240 reappearing. The display should show normal heating status. If the code returns, the sensor may need replacement or there may be a gas pressure or grounding issue.

When to Call a Professional

Contact a licensed HVAC technician if:

Sources

  1. Unit Information - icomfort ENABLED EL296UHV(X) Series Units

✓ Verified against manufacturer service manual — March 2026