HeatingCodesLennox furnace code E270: soft lockout, exceeded maximum retries, no flame sensed
What E270 means
Lennox lists E270 as Soft lockout - Exceeded maximum number of retries. No flame current sensed. The control tried to light the furnace more than its allowed number of times and never proved flame. The action required to clear is "check for proper gas flow. Ensure that ignitor is lighting burner. Check flame sensor current. Clears when heat call finishes successfully."
So the manual points at three things: gas reaching the burner, the hot surface igniter doing its job, and the flame sensor proving the flame. If the furnace never gets a stable flame, E270 shows. If it lights and then loses flame, the related code is E273.
Related ignition codes in the Lennox table
| Code | Meaning (per Lennox) | What the manual says |
|---|---|---|
| E270 | Soft lockout: exceeded maximum retries, no flame current sensed | Check gas flow, igniter lighting the burner and flame sensor current. |
| E273 | Soft lockout: exceeded maximum recycles, last recycle due to flame failure | Check flame sensor microamps. Clean or replace the sensor. Measure neutral-to-ground voltage to confirm a good unit ground. |
| E240 | Low flame current in run mode | Check flame sensor microamps. Clean or replace the sensor. The alert clears after the heat call. |
| E207 | Hot surface igniter sensed open | Measure the igniter resistance. Replace it if it is open or out of range. |
| E290 | Igniter circuit fault | 1-hour soft lockout. Measure igniter resistance and replace if open or out of specification. |
| E241 / E275 | Flame sensed out of sequence | Shut off gas and check for a gas valve leak. E275 is a 1-hour soft lockout. |
A flame signal that is present when it should not be (E241 and E275) is a safety issue. Lennox says to shut off gas. If you see either code, call a technician right away.
What a homeowner can and cannot do
Lennox expects a technician to measure microamps, igniter resistance and gas pressure. A homeowner can confirm that the gas is on (other gas appliances working), keep outdoor vent and intake terminations clear of snow, and wait for the lockout to clear. The control is built to try again on the next heat call, so a single E270 on a very cold morning is not an emergency, but repeats are.
Safe homeowner checks for Lennox furnace code E270
- Check that gas is availableSee whether another gas appliance is working. If you smell gas, leave and call your gas utility from outside.
- Clear outdoor vent and intake pipesFrom the ground, clear snow, ice or debris from the vent and combustion air terminations. Do not take the pipes apart or climb onto a roof.
- Turn off, wait and retry onceSet the thermostat below room temperature for a minute, then back to heat. Lennox says the soft lockout clears when a heat call finishes successfully.
- Call if it returnsIf E270 or E273 returns, call a heating technician. The cause may be the flame sensor, igniter, gas supply or venting.
Frequently asked questions
What is the difference between a soft and hard lockout on Lennox?
In the Lennox table a soft lockout clears on its own, often after one hour or when a heat call finishes successfully. A hard lockout such as E200 (rollout) requires the cause to be corrected or the switch replaced.
Does E270 mean the flame sensor is dirty?
A dirty sensor is one possible cause, and Lennox tells the technician to check flame sensor current. But E270 can also come from no gas, a weak igniter or blocked venting.
How do I find the code history?
The manual describes a diagnostic menu on the control, but it is aimed at technicians. Note the code you see and the time it happens and give both to your technician.
Sources
- Installation Instructions 508246-01 (04/2024): SL280DFV Elite Series gas furnace, Integrated Control Diagnostic Codes (Lennox) Covers: Lennox SL280DFV variable-capacity condensing gas furnaces with the integrated control described in the document. Other Lennox furnace lines can use different code sets.
Safety note: this page is general information drawn from the sources above. Gas, combustion and line-voltage repairs belong to a licensed professional. Your own equipment's label and manual take priority over anything here. Read the full disclaimer.