Lennox · Furnace

E161 Refrigerant leak sensor #2 wrong type

Medium severity Lennox ML180UHE

What the control is telling you

Sensor #2 is not a type approved for this application. Clears when a suitable sensor is detected; the blower then latches on for at least 5 minutes.

Applies to: ML180UHEK (R-454B era) single-stage 80% furnaces with integrated control 107792-XX (ML180UH045/070/090/110/135, incl. low-NOx X models)

Likely causes

Non-approved or wrong replacement sensor installed on LGWP2

Test and repair steps

Check the part number of sensor #2 against the approved sensor kit.
Replace with a Lennox approved sensor.
Press the LGWP test button to retest.

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Source: Lennox ML180UHEK Unit Information 100161/100166, Table 6 Integrated Diagnostic Codes, p.14. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.