Lennox EL296UHV Error Code E 116: High 24V Power
What Does Code E 116 Mean?
Code E116 on the Lennox EL296UHV means the 24V control-circuit voltage climbed above the acceptable window this board holds between 18 and 30 volts. The 24V is produced by a transformer that steps down the furnace's incoming line voltage, so an unusually high 24V reading almost always traces back to an incorrect or high input voltage feeding that transformer.
The classic cause is the furnace receiving the wrong supply voltage — for example, a 240V feed reaching a transformer expecting 120V — which drives the secondary output far too high. High utility voltage can contribute as well, though in that scenario the incoming-mains code E113 usually appears first. In either case the control raises E116 to protect the electronics from over-voltage on the control side.
The alarm clears once the control senses proper voltage again. Because E116 points at the supply feeding the furnace, verifying and correcting the line voltage at the disconnect is electrician work, not a homeowner repair. E116 is the high-side partner to E115 (24V too low): E115 typically means too much accessory load pulling the voltage down, while E116 means the input voltage is too high — distinguishing the two tells a technician which direction to investigate.
What You'll Notice
- "E 116" appears on the seven-segment LED indicating high 24V control power
- The code showed up after electrical work or a wiring change on the furnace circuit
- You suspect the furnace may be fed from the wrong voltage circuit
- The high-voltage incoming code E113 appears together with E116
- The furnace behaves erratically until the supply voltage is corrected
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Incorrect line voltage supplied to furnace | Most common | ✗ Call a pro → |
How This Is Diagnosed
A technician confirms the incoming line voltage at the furnace disconnect matches the nameplate rating, since a mismatched or high feed is the usual reason the 24V secondary reads high. Finding, for instance, a 240V feed on a 120V-configured unit explains E116 immediately.
If the incoming line voltage is correct but the 24V is still high, the transformer itself is suspect and may be producing excessive output. Because E116 clears when the control sees proper voltage, verification is confirming the 24V settles back into the 18-30V range once the supply is corrected.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- "E 116" is displayed, indicating high 24V control power
- You suspect the furnace is connected to the wrong voltage circuit
- The code appeared after electrical work on the home or the furnace feed
- E116 appears alongside E113 or other supply-voltage codes
Frequently Asked Questions
What usually causes high 24V power?
Most often the furnace is being fed the wrong incoming voltage, which makes the step-down transformer put out too much on its 24V side. High utility voltage can contribute too, but that typically shows as E113 first.
Can I correct E116 myself?
No. Verifying and correcting the incoming supply voltage means working at the line-voltage disconnect, which is electrician work. It is not a homeowner-safe repair.
How is E116 different from E115?
Both concern the 24V control circuit's 18-30V range, but E116 means the voltage is too high (usually a wrong or high supply) while E115 means it is too low (usually too many accessories loading the transformer).
✓ Verified against manufacturer service manual — March 2026