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Lennox · Furnace

E112 Ground not detected

High severity EL296UHVLennox SL280UHVLennox ML180UHELennox SL297NV

What the control is telling you

The control cannot detect an earth ground and shuts the system down.

Applies to: EL296UHV(X) series furnaces (integrated control 103130-XX and 107045-XX)

Likely causes

  • Missing or broken equipment ground

Test and repair steps

  1. Warning: Disconnect power before working on wiring.
  2. Verify the ground conductor is connected at the furnace and back to the panel.
  3. Check ground at the control AC volts between line neutral and the C terminal should not exceed 2 VAC at idle, 5 VAC with inducer/ignitor on, 10 VAC with blower on; a wide swing under load means a poor ground. Line hot to neutral should be 97-132 VAC.
  4. Repair or install a proper earth ground.
  5. Restore power; system resumes 5 seconds after the fault clears.

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Source: Lennox EL296UHV(X) Unit Information / Service Literature, Table 5 Ignition Control 103130-XX Diagnostic Codes, p.33; Ignition Control 107045-XX Diagnostic Codes table, p.40, Proper Ground and Voltage p.85. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

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.