HVACopediaLennox · Furnace
E152 Refrigerant leak sensor #2 fault
What the control is telling you
The second A2L (low GWP) refrigerant detection sensor reports an internal problem and may need replacing. Clears when the sensor stops reporting the fault.
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
- Failed refrigerant detection sensor #2
- Sensor contaminated or damaged
Test and repair steps
- Confirm a second sensor is actually installed and the LGWP2 DIP switch matches (Enable only with two sensors).
- Inspect sensor #2 and its plug for damage, dust, debris or moisture.
- Reseat the sensor connector at the LGWP2 plug until the Molex clip locks.
- If the fault stays, replace the sensor with a Lennox approved part.
- Press the LGWP test button (short press) to re-evaluate the fault after repair.
Settings for these units
Filter sizes by cabinet width · Lennox ML180UHE
| Cabinet | Side return | Bottom return |
|---|---|---|
| A - 14-1/2 in. | 16 x 25 x 1 (1) | 14 x 25 x 1 (1) |
| B - 17-1/2 in. | 16 x 25 x 1 (1) | 16 x 25 x 1 (1) |
| C - 21 in. | 16 x 25 x 1 (1) | 20 x 25 x 1 (1) |
| D - 24-1/2 in. | 16 x 25 x 1 (2) | 24 x 25 x 1 (1) |
Filters are field supplied; check monthly.
Cabinet letter is the letter after the cooling size in the model number: A = 045E36AK, 070E36AK; B = 070E36BK, 090E48BK; C = 090E60CK, 110E60CK; D = 135E60DK.
Models that show this code
12 models in Lennox ML180UHE
Other codes on the same units
- E150 A2L refrigerant leak alarm
- E151 A2L sensor fault
- E154 Refrigerant leak sensor #1 communication lost / wrong DIP setting
- E155 Refrigerant leak sensor #2 communication lost
- E160 Refrigerant leak sensor #1 wrong type
- E161 Refrigerant leak sensor #2 wrong type
- E163 Furnace control board failure
- E164 Low GWP test mode active
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Source: Lennox ML180UHEK Unit Information 100161/100166, Table 6 Integrated Diagnostic Codes, p.14; VII Low GWP Application, p.33-35. 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.