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Lennox · Furnace

E117 Poor ground detected

Medium severity EL296UHVLennox SL280UHVLennox ML180UHELennox SL297NV

What the control is telling you

Warning only: the ground connection is marginal.

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

Likely causes

  • Weak or high-resistance ground connection

Test and repair steps

  1. Warning: Disconnect power before tightening ground connections.
  2. Inspect and tighten ground connections at the furnace and 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. Verify proper earth ground to the system.
  5. Warning clears 30 seconds after the fault is fixed.

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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.

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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.