Lennox Furnace Error Codes

A premium HVAC manufacturer known for high-efficiency furnaces, founded in 1895 in Marshalltown, Iowa.

Disclaimer
This site is not affiliated with or endorsed by Lennox International Inc.

How Lennox Furnaces Display Error Codes

The SureLight integrated control displays diagnostic codes and status information on a seven-segment LED display. Status codes indicate current operating mode. Error codes (prefixed with 'E') indicate faults. Idle mode shows a decimal point blinking at 1 Hertz (0.5 second ON, 0.5 second OFF). Status indicators use different blink patterns: 1 second ON with 0.5 second OFF for gas heat and cooling stages, 0.5 second ON with 1 second OFF for dehumidification mode, etc. Error codes display as 'E' followed by a numeric code.

This site covers 2 Lennox furnace models and a total of 122 error code entries. Select your model below to see the full code list with causes and repair guidance.

Lennox Furnace Models

Model Type
EL296UHV Two Stage Gas Furnace →
SLP98UHV Modulating Gas Furnace →

DIY-Friendly Lennox Error Codes

These error codes on Lennox furnaces are commonly resolved by a careful homeowner without a service call — typically by cleaning the flame sensor, checking filters, or inspecting the exhaust vent. Always turn off power and gas before attempting any repair.

Code Fault Models
E 252 Discharge Air Temperature Too High 2 models
E 291 Heat Air Flow Restricted Below Minimum 2 models
E 250 Limit Switch Circuit Open 2 models
E 274 Soft Lockout - Limit Open 2 models
E 403 LSOM - Compressor Short-Cycling SLP98UHV
E 312 Restricted Airflow - Cooling/Fan Mode SLP98UHV

High-Severity Lennox Error Codes

These codes indicate conditions that prevent normal furnace operation or involve safety-relevant components such as the gas valve, heat exchanger, or inducer motor. Most require a licensed HVAC technician to diagnose and repair safely.

Code Fault Models
E 203 Appliance Capacity Not Programmed 2 models
E 294 Combustion Air Inducer Over Current 2 models
E 126 Control Internal Communication Problem 2 models
E 125 Control Self-Check Failure 2 models
E 252 Discharge Air Temperature Too High 2 models
E 241 Flame Sensed Out of Sequence 2 models
E 205 Gas Valve Control Relay Contact Shorted 2 models
E 204 Gas Valve Mis-Wired 2 models

About Lennox

Lennox was founded in 1895 in Marshalltown, Iowa, by Dave Lennox, who ran a machine repair business for railroads. After obtaining patent rights to a riveted steel coal-fired furnace design, Lennox established the Lennox Furnace Company. DW Norris acquired the business in 1904 and managed it until 1949, with his descendants retaining significant ownership today.

The company expanded its portfolio through strategic acquisitions, including Heatcraft in 1973 and multiple commercial refrigeration brands over subsequent decades. Lennox went public via an IPO in 1999 and is now headquartered in Richardson, Texas. Its Marshalltown manufacturing facility, damaged by a tornado in 2018, was rebuilt and continues to employ over 750 workers. Today, Lennox International is an S&P 500 company trading on the NYSE under ticker LII with roughly 14,200 employees worldwide.

Lennox in the Furnace Market

Lennox International is a leading manufacturer of climate control products for residential and commercial markets, reporting approximately $5.34 billion in revenue in 2024. The company operates through two divisions: Home Comfort Solutions, which includes the Lennox, Armstrong Air, Ducane, and AirEase brands, and Building Climate Solutions, which covers commercial refrigeration through Heatcraft Worldwide Refrigeration and related brands. Lennox differentiates itself through premium energy-efficient systems, award-winning design, and an industry-wide reputation for quiet operation and indoor air quality innovation.