The short answer
E200 on a Lennox furnace in Northern Virginia is a hard lockout: the flame rollout circuit is open, or it was open. A rollout switch trips when flames come out of the burner area instead of going through the heat exchanger and up the vent. The furnace stays off until someone cycles the power, and it should stay off until someone finds out why. Don’t keep resetting it. Call.
If you smell gas, skip all of it. Leave the house and call the gas company and 911 from outside. If a carbon monoxide alarm is going off, get everyone out first (what to do when the CO alarm sounds).
What a rollout switch does
A gas furnace burns in a small box and pushes the hot gases through the heat exchanger and out the vent. The rollout switches are little heat-sensing switches mounted right at that burner box. If the vent is blocked or the heat exchanger can’t carry the gases away, the flame rolls back out toward you instead. The switch feels that heat and cuts the gas.
That’s why E200 is a hard lockout and not a soft one. Lennox doesn’t let the furnace retry on its own after a rollout. The service manual’s fix is “correct cause of rollout trip or replace flame rollout switch,” in that order.
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E200 is a rollout code, whatever you read
Some charts online call E200 something else. Lennox’s own service manuals for the SL280, EL296, EL280 and SLP99 furnaces all list it as “hard lockout, rollout circuit open or previously open.” “Previously open” matters: the switch may have closed again by the time you look, and the code still stands.
On a Merit furnace with a red light, a rollout trip blinks 5 flashes on an ML180UH or ML195UH, 8 flashes on an ML180UHE, and 4 flashes on an ML296UHV, where 4 also covers the limit switches.
What causes a rollout
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| The cause | What a tech checks |
|---|---|
| A blocked vent or flue | Snow, leaves or a nest in the vent ends outside, a sagging or disconnected pipe inside |
| A cracked or plugged heat exchanger | Inspects it, and checks for carbon monoxide at the furnace |
| Dirty or misaligned burners | Flame shape and where it’s pointing |
| Gas pressure set too high | Measures it at the gas valve |
| A failed rollout switch | Tests the switch and its wiring with a meter, after the other four |
The last one is real, but it’s the one to rule in last. Swapping a rollout switch without finding why it tripped is how a furnace with a blocked vent gets put back in service.
What to do right now
Leave the furnace off. Turn the thermostat to off. Use space heaters on a safe circuit if you need them.
Check your carbon monoxide alarm. If it’s going off, or anyone has a headache, nausea or dizziness, get everyone outside and call 911. If there’s no alarm, put one in (CO alarm going off).
Look at the vent pipes outside. On a high-efficiency furnace, the two white pipes on the side of the house can drift over with snow or fill with leaves. Clearing them is safe. Don’t restart the furnace yourself after, though; it still needs a look.
Don’t push the button. Some rollout switches have a small reset button. The switch tripped for a reason, and pushing it again just lets the same flame roll out again.
What it costs
The diagnostic is a flat $99. A rollout switch, a vent repair or a burner cleaning gets priced in writing once we know which one it is. If it turns out to be a cracked heat exchanger, you’re looking at a furnace decision, not a part (cracked heat exchanger).
If the repair is a big one on an older furnace, get a second look before you spend it. Our free second opinion costs you nothing, and the estimator shows what a new system costs with $1,500 off already in the price. Thinking about brands? Lennox vs Trane lays out the difference.
Every Lennox code in one place: Lennox error codes.
The system we put in first
Built to take a beating. Put in by our crew.
Heat lamps, snow and rain on one outdoor unit: that’s Trane’s own film. We’re a Trane Comfort Specialist, on Trane’s own dealer locator, and when you pick a Trane, our crew puts it in.
Films: Trane’s own.
Call or book a Lennox repair
Call (703) 997-9757. We answer day or night. Or book online and pick a time. The diagnostic is a flat $99, and you see the repair price in writing before we touch anything. Furnace running fine and you want to keep it that way? Book the $67 heating check from goswiftpro.com/cookiesoffer (book by November 30) and a box of warm cookies comes with the visit. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276. More on Lennox repair in Northern Virginia.
Questions people ask
What does E200 mean on a Lennox furnace?
It’s a hard lockout because the flame rollout circuit is open or was open. Flames came out of the burner area, usually because the vent or heat exchanger couldn’t carry the combustion gases away.
Can I reset a Lennox E200 code?
Cycling the power clears it, but you shouldn’t until someone finds out why it tripped. A rollout usually points at a blocked vent, a heat exchanger problem or gas pressure.
Is a Lennox rollout switch trip dangerous?
It can be. The switch exists to stop a fire and carbon monoxide when flames roll out of the burner box. Leave the furnace off and check that your CO alarm works.
What causes a Lennox rollout switch to trip?
A blocked vent or flue, a cracked or plugged heat exchanger, dirty burners, gas pressure set too high, or, less often, a failed switch.
