Lennox gas furnaces show codes such as E228 or E313 on the control board display or the thermostat, and some boards flash LED patterns instead. Below are 31 Lennox codes across 1 model series. Each one says what it means, which series it applies to, what you can safely check, and when to call a licensed pro, with a link to the Lennox document it comes from.
The same code can mean different things on different series, so match the series column to your unit. Your unit's manual is the final word. Reviewed October 2026.
31 codes
| Code | Meaning | Applies to | Safety |
|---|---|---|---|
| E110 Shown as an E code on the 7-segment display of the integrated control | AC line voltage low | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E111 Shown as an E code on the 7-segment display of the integrated control | Line voltage polarity reversed | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E112 Shown as an E code on the 7-segment display of the integrated control | Earth ground not detected | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E113 Shown as an E code on the 7-segment display of the integrated control | AC line voltage high | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E115 Shown as an E code on the 7-segment display of the integrated control | Low 24V control voltage | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E200 Shown as an E code on the 7-segment display of the integrated control | Rollout open (hard lockout) | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E204 Shown as an E code on the 7-segment display of the integrated control | Gas valve relay problem | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E206 Shown as an E code on the 7-segment display of the integrated control | Gas valve second-stage relay problem | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E223 Shown as an E code on the 7-segment display of the integrated control | Low pressure switch failed to close | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E224 Shown as an E code on the 7-segment display of the integrated control | Low pressure switch failed to open | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E225 Shown as an E code on the 7-segment display of the integrated control | High pressure switch failed to close | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E226 Shown as an E code on the 7-segment display of the integrated control | High pressure switch failed to open | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E227 Shown as an E code on the 7-segment display of the integrated control | Low pressure switch opened during run | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E241 Shown as an E code on the 7-segment display of the integrated control | Flame sensed out of sequence | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E250 Shown as an E code on the 7-segment display of the integrated control | Primary limit switch opened | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E124 Shown as an E code on the 7-segment display of the integrated control | Thermostat (subnet controller) missing | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E201 Shown as an E code on the 7-segment display of the integrated control | Cannot communicate with blower motor | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E205 Shown as an E code on the 7-segment display of the integrated control | Gas valve relay contacts shorted | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E207 Shown as an E code on the 7-segment display of the integrated control | Hot surface igniter open | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E270 Shown as an E code on the 7-segment display of the integrated control | Lockout: flame failure on ignition | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E271 Shown as an E code on the 7-segment display of the integrated control | Lockout: pressure switch open at ignition | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E272 Shown as an E code on the 7-segment display of the integrated control | Lockout: pressure switch open during run | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E273 Shown as an E code on the 7-segment display of the integrated control | Lockout: flame lost during run | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E274 Shown as an E code on the 7-segment display of the integrated control | Lockout: limit open over 3 minutes | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E275 Shown as an E code on the 7-segment display of the integrated control | Lockout: flame out of sequence, now gone | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E290 Shown as an E code on the 7-segment display of the integrated control | Igniter circuit fault | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🛑 Call a pro |
| E292 Shown as an E code on the 7-segment display of the integrated control | Indoor blower unable to start | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E240 Shown as an E code on the 7-segment display of the integrated control | Low flame current in heating mode | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E311 Shown as an E code on the 7-segment display of the integrated control | Restricted airflow, heat rate reduced | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
| E312 Shown as an E code on the 7-segment display of the integrated control | Restricted airflow, cooling or fan mode | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | ✅ Keep running |
| E117 Shown as an E code on the 7-segment display of the integrated control | Poor ground detected | Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display) | 🧭 Check first |
✅ Usually fine to keep running · 🧭 Check a few things first · 🛑 Turn it off and call a licensed pro
The codes Lennox documents for each series we have checked. If your series is not listed, the code may mean something different on your unit, so check its manual.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports the AC line voltage is low. It is listed as an electrical fault where the control waits for recovery.
When to call a pro: Call a licensed technician if the code returns. Supply voltage must be measured by a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports the line voltage polarity is reversed. This is a wiring fault.
When to call a pro: Call a licensed technician. Line voltage wiring must be corrected by a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control does not detect an earth ground. This is a wiring fault.
When to call a pro: Call a licensed technician. Grounding must be fixed by a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports the AC line voltage is high. It is listed as an electrical fault where the control waits for recovery.
When to call a pro: Call a licensed technician if the code returns. Supply voltage must be measured by a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports low 24 volt power and restarts if the error recovers.
When to call a pro: Call a licensed HVAC technician if the code returns or the furnace will not restart.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports a problem with the first or second stage gas valve relay.
When to call a pro: Call a licensed HVAC technician. Gas valve and control faults must be checked by a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports a problem with the second stage gas valve relay.
When to call a pro: Call a licensed HVAC technician. The gas valve circuit must be checked by a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The low pressure switch failed to open (stuck closed).
When to call a pro: Call a licensed HVAC technician to test the pressure switch and inducer.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The high pressure switch failed to close (stuck open).
When to call a pro: Call a licensed HVAC technician. Pressure, venting and the inducer need professional testing.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The high pressure switch failed to open (stuck closed).
When to call a pro: Call a licensed HVAC technician to test the pressure switch and inducer.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
A communication code. The active subnet controller (communicating thermostat) has been missing for more than 3 minutes.
When to call a pro: Call a licensed HVAC technician if the furnace and thermostat still do not communicate.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control is unable to communicate with the indoor blower (circulator) motor. It is listed as a 60 minute soft lockout fault.
When to call a pro: Call a licensed HVAC technician. The motor, wiring or control may need service.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports the gas valve relay (first or second stage) contacts are shorted. It is listed as a 60 minute soft lockout fault.
When to call a pro: Call a licensed HVAC technician. This is a gas valve or control fault.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
Soft lockout. The furnace exceeded its ignition retries and the last failed retry was due to the low pressure switch opening.
When to call a pro: Call a licensed HVAC technician. Venting and pressure switch checks need professional tools.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
Soft lockout. Heating recycles exceeded the maximum and the last failed retry was due to the low pressure switch opening in run mode.
When to call a pro: Call a licensed HVAC technician to inspect the vent, inducer and pressure switch.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
Soft lockout. Heating recycles exceeded the maximum and the last failed retry was due to loss of flame in run mode.
When to call a pro: Call a licensed HVAC technician. Flame sensor and gas checks are for a professional.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
Soft lockout. Flame was sensed out of sequence and is now gone.
When to call a pro: Call a licensed HVAC technician right away.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports an igniter circuit fault, from either a failed igniter or the triggering circuitry.
When to call a pro: Call a licensed HVAC technician to test the igniter and control.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
The control reports the indoor blower is unable to start.
When to call a pro: Call a licensed HVAC technician. The motor or wheel may need service. Do not open the blower compartment.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
Airflow in cooling or continuous fan mode is restricted. The manual labels it information only.
When to call a pro: Call a licensed HVAC technician if the code continues after a clean filter and open vents.
Applies to: Lennox SL280UHVK two-stage variable-speed furnace (integrated control, 7-segment display). Shows as: Shown as an E code on the 7-segment display of the integrated control
A performance warning. The control detects a poor ground.
When to call a pro: Call a licensed technician. Grounding must be checked by a professional.
Shaun Cain · Certified HVAC & Refrigeration Technician · Ask an HVAC technician