If your Lennox furnace is showing a code like E200 or E250, that's an alert from the SureLight or iComfort control board telling you exactly why it stopped. Lennox uses 3-digit alert codes shown on a 7-segment display on the board (or, on iComfort systems, on the thermostat). The good news is these codes are specific — once you read the number correctly, you're most of the way to knowing whether it's an airflow issue you can help with or a safety lockout that needs a tech.
Reading the code: Lennox alert codes are three digits with an E prefix — read them off the 7-segment display on the control board behind the access panel, or from an iComfort thermostat. A bare "E1" or "E2" is not a Lennox furnace code — that's generic thermostat or mini-split content and doesn't map to the Lennox alert chart. As always, code meanings can vary by control-board generation, so confirm the number against the diagnostic label printed inside the furnace's access panel before you buy any part.
Lennox furnace alert codes
| Code | Meaning | Typical cause |
|---|---|---|
| E200 | Flame rollout switch open — hard lockout | Flame rollout from a blocked heat exchanger, plugged burners, or poor venting/combustion air |
| E201 | Lost communication with the indoor blower motor | Brownout / low voltage, loose motor harness, or a failing blower motor or board |
| E207 | Hot-surface igniter sensed open | Cracked or burned-out hot-surface igniter, or its wiring |
| E223 ⚠ | Conflicting sources — see note below | Official Lennox: low-pressure switch open. Many aggregators list it as a high-limit fault. Verify on the unit. |
| E227 | Low-pressure switch open | Venting or inducer restriction, blocked intake/exhaust, clogged condensate, or a weak inducer |
| E250 | Primary limit switch open | Dirty filter, restricted airflow/ducts, closed vents, or high gas pressure (over-firing) |
| E270 | Soft lockout — flame not proven after 5 tries | Dirty flame sensor, weak igniter, low gas, or a gas-valve issue |
About E223: this is the code where sources disagree. Lennox's own documentation lists E223 as a low-pressure switch fault, while many third-party charts list it as a high-limit fault. We don't guess between them — we read the code on your specific board and verify against the diagnostic label inside your unit before acting. Where two sources conflict, the label on your furnace is the authority.
What the codes are telling you
Lennox alerts sort into a few families:
- Safety lockouts (E200). A rollout lockout is the serious one — it means flame escaped the burner area. This is a hard lockout for a reason; it needs a tech, not a reset.
- Airflow / limit (E250). The furnace overheated because air isn't moving — almost always a dirty filter or restricted ducts. The most DIY-friendly Lennox code.
- Venting / pressure (E227, and possibly E223). The pressure switch confirms the inducer is drawing combustion gases out safely; an open switch points to a blocked vent, clogged condensate, or a weak inducer.
- Ignition / flame (E207, E270). These center on the igniter, flame sensor, and gas valve. A cleaned flame sensor clears many E270 soft lockouts.
- Blower comms (E201). Often a low-voltage/brownout event or a wiring/motor fault.
Common causes
Most common first, across the codes above:
- Dirty air filter or restricted ducts — behind most E250 limit trips.
- Dirty flame sensor — the usual reason for an E270 soft lockout.
- Blocked vent, clogged condensate, or weak inducer — behind E227 (and possibly E223).
- Failed hot-surface igniter — the E207 code.
- Rollout from a blocked heat exchanger or poor combustion — the E200 lockout.
The usual fix
Our tech reads the stored code, then confirms it: check and change the filter, clean or replace the flame sensor, verify the inducer and venting draw properly, test the pressure and limit switches, and inspect the igniter and gas pressure. On an E200 rollout lockout, we inspect the heat exchanger and combustion path carefully before returning the furnace to service. Many Lennox calls end with restored airflow or a cleaned sensor; when a part has truly failed, we replace it and confirm a full, clean heat cycle.
DIY vs. calling a pro
Safe to try yourself first (free):
- Turn the furnace off and change a dirty filter, wait 20–30 minutes, and restart — this clears a large share of E250 codes.
- Open blocked supply and return vents and clear anything over a return.
- Power-cycle at the switch or breaker to reset a soft lockout after fixing airflow.
Call a pro when:
- You see an E200 rollout lockout — do not repeatedly reset it; flame rollout is a safety issue.
- A code returns after a fresh filter (E227, E270, E207 especially), or you see E223 and need the meaning confirmed.
- The blower won't run (E201), or you smell a hot/burning odor.
Gas, line-voltage electrical, and any refrigerant or compressor work belong with a licensed technician (EPA 608 certified for refrigerant handling). A furnace that keeps overheating or rolling out can crack the heat exchanger, which is a carbon-monoxide risk.
What it costs in the Bay Area
Many Lennox codes resolve with a filter or a cleaned flame sensor. When a part is needed, in our pricing a flame sensor runs about $90–$250, a hot-surface igniter $120–$350, and a control board $200–$600, depending on model. We charge a diagnostic fee that's credited toward the repair when you approve the work, with a firm, upfront price before any work begins.
Book Lennox furnace service
Triton services Lennox furnaces — plus every major brand — across the SF Bay Area & Peninsula, with same-week and often same-day appointments. If your Lennox is showing E200, E250, or another alert, we'll read it correctly and get your heat back safely.
Call (888) 993-5699 or book online for same-day furnace service.
Related pages
- HVAC Repair in the SF Bay Area — our full heating & cooling hub
- Furnace Not Heating / No Heat — the symptom behind a lockout
- Carrier Furnace Code 33 (Limit Circuit Fault) — the same airflow limit trip on Carrier
- Lennox HVAC Repair — brand service hub
- Furnace Repair in San Mateo — same-day service in your city
Frequently asked questions
What does E200 mean on a Lennox furnace? E200 is a flame rollout switch open, and it is a hard lockout. It means flame escaped the burner area, usually from a blocked heat exchanger, plugged burners, or poor venting and combustion air. Do not keep resetting it. This is a safety code that needs a technician to inspect the heat exchanger and combustion path.
What does E250 mean on a Lennox furnace? E250 is an open primary limit switch: the furnace overheated because air was not moving fast enough to carry the heat away. The most common causes are a dirty filter, restricted ducts, or closed vents. Start with a fresh filter and open registers, then restart. If it returns, the restriction is deeper.
What does E270 mean on a Lennox furnace? E270 is a soft lockout after flame was not proven in five tries. It usually traces to a dirty flame sensor, a weak hot-surface igniter, low gas pressure, or a gas-valve issue. Cleaning the flame sensor clears many of these, but repeated E270 lockouts should be checked by a technician.
Is E1 or E2 a Lennox furnace error code? No. Lennox furnaces use three-digit alert codes such as E200 and E250. A bare E1 or E2 is generic thermostat or mini-split content and does not map to the Lennox furnace chart. Read the actual three-digit code off the control board display or the iComfort thermostat.
What does E223 mean on a Lennox furnace? Sources conflict on E223. Lennox documentation lists it as a low-pressure switch fault, while many third-party charts list it as a high-limit fault. We do not guess. We read the code on your specific board and confirm it against the diagnostic label inside your unit before acting.
How much does Lennox furnace repair cost in the Bay Area? Many codes resolve with a filter or a cleaned flame sensor. When a part is needed, a flame sensor runs about 90 to 250 dollars, a hot-surface igniter 120 to 350 dollars, and a control board 200 to 600 dollars, depending on model. We credit the diagnostic fee toward the repair and quote a firm price first.