MEDIUM URGENCY

Lennox E241 - Flame Sensor Fault

E241

Flame sensor reporting incorrect readings or zero signal.

Brand: Lennox (Also covers Armstrong Air, Aire-Flo, Ducane) | Equipment: Gas Furnace

What This Code Means

Error code E241 on Lennox iComfort means the flame sensor is reporting incorrect readings. Could be a heavily coated sensor, broken sensor, or wiring issue.

Likely Causes (Ranked)

Most common

Heavily coated flame sensor

What: Severe carbon or oxide buildup completely blocks signal.

How to check: Pull sensor; visible coating.

Fix: Clean thoroughly with emery cloth.

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Common

Broken flame sensor rod

What: Ceramic insulator cracked or rod broken.

How to check: Visual inspection.

Fix: Replace flame sensor.

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Less common

Wiring fault

What: Broken or shorted wire to sensor.

How to check: Inspect connections.

Fix: Repair wiring.

Diagnostic Steps

Cut power
Pull flame sensor
Inspect for damage and clean
Replace if cracked
Check wiring

Frequently Asked Questions

Difference between Lennox E240 and E241?

E240 = weak signal (sensor dirty); E241 = no/erratic signal (sensor failed or wiring fault).

DIY?

Yes - flame sensor cleaning or replacement is straightforward.

Cost?

Sensor is $15-40 part.

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Need More Help?

Try our interactive symptom diagnostic tool or browse Lennox parts.

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