Lennox SLP98UHV Error Code E 110: Low Line Voltage
What Does Code E 110 Mean?
Error code E110 on the Lennox SLP98UHV indicates that the line voltage supplying the furnace is lower than the nameplate rating. The control board continuously monitors the incoming voltage and flags this error when it drops below the acceptable threshold.
Low voltage can be caused by a utility-side issue such as a brownout condition, where the power company delivers reduced voltage during high-demand periods. It can also result from a problem on the home's electrical system — an undersized circuit, a loose connection at the breaker panel, corroded wiring, or too many appliances sharing the same circuit can all reduce the voltage reaching the furnace.
Operating a furnace on low voltage can damage the control board, blower motor, and other electronic components. The motors may run hotter than normal, and the control board may behave erratically. An electrician should measure the voltage at the furnace disconnect and at the electrical panel to determine whether the issue is on the utility side or within the home's wiring.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Utility power supply issue or brownout condition | Most common | ✗ Call a pro → |
| Undersized or overloaded electrical circuit | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace needs its electrical supply voltage checked by an electrician
- You notice lights flickering or dimming in your home, suggesting a utility power issue
- E110 appears during periods of high neighborhood electrical demand
- The furnace circuit breaker or wiring needs professional inspection
✓ Verified against manufacturer service manual — March 2026