HVACopediaLennox · Furnace
E117 Poor ground detected
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
- Warning: Disconnect power before tightening ground connections.
- Inspect and tighten ground connections at the furnace and panel.
- 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.
- Verify proper earth ground to the system.
- Warning clears 30 seconds after the fault is fixed.
Settings for these units
Recommended filter size by cabinet width · EL296UHV
| Cabinet width | Side return | Bottom return |
|---|---|---|
| 17-1/2 in. | 16 x 25 x 1 in. (1) | 16 x 25 x 1 in. (1) |
| 21 in. | 16 x 25 x 1 in. (1) | 20 x 25 x 1 in. (1) |
| 24-1/2 in. | 16 x 25 x 1 in. (2) | 24 x 25 x 1 in. (1) |
Number in brackets is the quantity of filters.
Filters are field supplied and installed outside the furnace; inspect monthly.
Recommended filter size by cabinet width · Lennox SL280UHV
| Cabinet width | Side return | Bottom return |
|---|---|---|
| 14-1/2 in. | 16 x 25 x 1 in. (1) | 14 x 25 x 1 in. (1) |
| 17-1/2 in. | 16 x 25 x 1 in. (1) | 16 x 25 x 1 in. (1) |
| 21 in. | 16 x 25 x 1 in. (1) | 20 x 25 x 1 in. (1) |
| 24-1/2 in. | 16 x 25 x 1 in. (2) | 24 x 25 x 1 in. (1) |
Number in brackets is filter quantity; filters are field supplied.
Never run the unit without a filter installed.
- Filter sizes by cabinet width · Lennox ML180UHE
- Filter sizes by cabinet width · Lennox SL297NV
Models that show this code
34 models in EL296UHV, Lennox SL280UHV, Lennox ML180UHE, Lennox SL297NV
Other codes on the same units
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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.