Lennox Furnace Error Code E113

E113 means the furnace control board has detected that incoming line voltage is higher than the unit's nameplate rating. The furnace shuts down automatically to protect its electrical components from damage caused by overvoltage. The system will resume normal operation on its own approximately 5 seconds after the voltage returns to an acceptable level. The fault points to an issue with the electrical supply rather than a mechanical component inside the furnace.

Yes, persistent overvoltage is a legitimate safety and equipment concern. Sustained high voltage can overheat motor windings, degrade insulation on electrical components, and shorten the lifespan of the control board and other electronics. A lost neutral condition at the electrical panel, which is one potential cause, is a serious electrical hazard that can damage appliances throughout the home and should be addressed by a licensed electrician immediately.

The repair cost depends entirely on the root cause. If the issue is a utility supply problem, your utility company may correct it at no charge. If a licensed electrician is needed to repair a panel connection or fix a wiring error, expect costs in the range of $100 to $400 or more depending on the complexity of the work. If the furnace control board itself has failed and needs replacement, parts and labor typically range from $300 to $700.

Start by measuring the actual line voltage at the furnace disconnect or power junction using a true-RMS voltmeter and comparing it to the voltage listed on the furnace nameplate. If voltage is elevated, check your home's main panel for loose connections and contact your utility provider to report a possible transformer issue. If all supply voltages measure correctly, suspect the furnace control board's voltage-sensing circuit and consult a certified HVAC technician for further diagnosis.

A manual reset is not required for E113. The furnace will automatically clear the fault and resume normal operation within 5 seconds once the incoming voltage drops back into the acceptable range. If you power cycle the furnace while the overvoltage condition still exists, the error will return immediately. The underlying supply voltage problem must be corrected first.