Newer Lennox furnaces display error codes on a small digital readout on the control board, such as E 223 (low pressure switch failed open), E 250 (limit switch circuit open) or E 270 (lockout after the maximum number of ignition retries without flame). Older Lennox furnaces use two LEDs that flash in combinations instead. Below are the codes used on Lennox integrated controls with a display, from Lennox’s own service literature, plus what to do for the most common ones.
Before you start
- Record the code before turning off power. Some boards clear it when power is cut.
- Confirm with the label inside your furnace’s blower door. Codes can differ between control boards and model years.
- Reset only once or twice. Turn off power for 30 seconds and restore it. A code that comes back means a real problem.
- Safety: if you smell gas, leave the home and call your gas utility or 911 from outside. Never bypass a safety switch.
How to read Lennox codes
- Digital display: look through the blower door sight glass. The control shows the current status and, on a fault, an “E” code with a three-digit number. Many Lennox controls also have a button or menu to recall stored codes; follow the label on your furnace.
- Two-LED boards (older models): codes are shown as combinations of the red and green LEDs (for example, both flashing, one steady and one flashing). Use the chart on the label inside your blower door, because the combinations vary by board.
Lennox furnace error codes
| Code | Meaning |
|---|---|
| E 110 | Low line voltage |
| E 111 | Line voltage polarity reversed |
| E 112 | Ground not detected |
| E 113 | High line voltage |
| E 114 | Line voltage frequency out of range |
| E 115 | Low 24-volt power |
| E 117 | Poor ground detected (warning only) |
| E 125 | Control failed self-check (internal hardware error) |
| E 200 | Hard lockout: rollout circuit open or previously open |
| E 204 | Gas valve miswired |
| E 205 | Gas valve control relay contact shorted |
| E 206 | Gas valve second-stage relay failure |
| E 207 | Hot surface igniter sensed open |
| E 223 | Low pressure switch failed open |
| E 224 | Low pressure switch failed closed |
| E 225 | High pressure switch failed open |
| E 226 | High pressure switch failed closed |
| E 227 | Low pressure switch opened during ignition or while running |
| E 229 | Ignition on high fire (information only) |
| E 240 | Low flame current while running |
| E 241 | Flame sensed out of sequence; flame still present |
| E 250 | Limit switch circuit open |
| E 270 | Soft lockout: maximum ignition retries exceeded, no flame sensed |
| E 271 | Soft lockout: maximum retries exceeded, last retry failed on pressure switch |
| E 272 | Soft lockout: maximum recycles exceeded due to pressure switch opening |
| E 273 | Soft lockout: maximum recycles exceeded due to flame failure |
| E 274 | Soft lockout: maximum recycles exceeded due to limit circuit |
| E 275 | Soft lockout: flame sensed out of sequence; flame signal now gone |
| E 290 | Igniter circuit fault |
Source: Lennox EL296DFE service literature. Other Lennox models, including variable-speed and iComfort communicating furnaces, use additional codes (for example blower and inducer motor faults) and may show them on the thermostat. Always check your model’s literature.
What to do for the most common codes
E 270 to E 273: soft lockout
The furnace failed to light or keep flame several times and paused. It usually retries after about an hour.
- Make sure the gas valve is open.
- Clean the flame sensor: how to clean a furnace flame sensor.
- If the igniter doesn’t glow (also see E 207 and E 290): furnace ignitor not glowing.
E 223, E 225, E 227 and E 271/E 272: pressure switch
- Clear the outdoor PVC vent and intake pipes of snow, ice and debris.
- Check the condensate trap and drain, and the pressure switch hose for water or cracks.
- If they’re clear, a technician should check the inducer motor and switch.
E 250 and E 274: limit circuit
- Replace the air filter and open all vents: how often to change your air filter.
- If it repeats, have the blower and limit switch checked.
E 200: hard lockout, rollout circuit
A rollout switch trips when flames roll out of the burner area, which can point to a blocked vent or a cracked heat exchanger. This requires a technician; don’t keep resetting it.
E 240: low flame current
Clean the flame sensor and check grounding (E 112 and E 117 also point to grounding).
When to call a technician
Call a licensed HVAC technician if the same code returns after one reset, or right away for rollout switch, flame-sensed-with-gas-valve-off, gas valve, polarity or control board codes. Give the technician the code, the furnace model number and when the problem started; it speeds up the repair.
For a complete troubleshooting sequence, see Furnace Not Turning On: 11 Causes and Fixes. For other brands, see our furnace blinking light codes guide.
For a deeper look at the two most common faults behind these codes, see furnace pressure switch problems and furnace high limit switch tripping.
Disclaimer: this guide is for general information only and summarizes common Lennox control board codes. Codes vary by model and board; always confirm with the label inside your furnace or the manufacturer’s literature. Gas furnaces involve gas, combustion and high voltage. Contact a licensed HVAC professional for repairs.