Lennox SLP98UHV Error Code E 114: Line Voltage Frequency Out-of-Range
What Does Code E 114 Mean?
Error code E114 on the Lennox SLP98UHV indicates that the line voltage frequency is outside the acceptable range. In North America, the electrical grid operates at 60 Hz, and the control board expects to see this frequency. When it detects a different frequency, it flags E114.
The most common scenario where this occurs is when the furnace is being powered by a portable generator that is not producing a clean 60 Hz signal. Cheap or overloaded generators can deliver inconsistent frequency that the control board rejects. A utility power issue affecting the frequency is possible but rare.
The SLP98UHV's variable-speed motors and advanced control electronics rely on stable power frequency for proper operation. Running on incorrect frequency can cause motors to run at wrong speeds, control timing to be off, and electronic components to malfunction. An electrician should check the power quality at the furnace. If the furnace is on generator power, verify the generator is producing clean 60 Hz output and is not overloaded.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Abnormal utility power supply or generator with incorrect frequency | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The power supply frequency needs to be tested with proper instruments
- The furnace is being powered by a generator that may not be producing clean power
- E114 appears during normal utility power operation, suggesting a power quality problem
✓ Verified against manufacturer service manual — March 2026