Lennox EL296UHV Error Code E 117: Poor Ground Detected
What Does Code E 117 Mean?
Error code E117 on the Lennox EL296UHV is a warning that the control board has detected a degraded ground connection. Unlike E112 (ground not detected), which shuts the system down, E117 is a warning-only code — the furnace continues to operate but with reduced safety margin.
A poor ground connection means the earth ground path has higher resistance than expected. This can be caused by a loose ground wire terminal at the furnace, corrosion on the ground wire or its connection points, or a degraded grounding electrode at the electrical panel. Over time, connections can loosen from thermal cycling and vibration.
The warning clears automatically 30 seconds after the ground quality improves. While the furnace will continue to operate with this warning, proper grounding is important for flame sensing accuracy and electrical safety. Have an electrician check and tighten the ground connections at the furnace and verify the integrity of the ground path back to the panel.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Loose or corroded ground wire connection | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The E117 warning appears consistently
- The furnace also shows flame sensing or polarity errors
- The ground wire connection appears corroded or loose
✓ Verified against manufacturer service manual — March 2026