Lennox Error Code E117 indicates Poor ground detected (warning only). Start by checking the most common and safe items identified in the troubleshooting section. If the code returns after those checks, professional diagnosis is recommended.
Easy
Poor ground detected (warning only)
Unknown
Improper or poor grounding
Provide proper grounding; warning clears 30 seconds after fault recovery
Grounding system
Call an HVAC technician if the error persists after completing the recommended basic troubleshooting steps or if the system repeatedly locks out.
Disconnect power before inspecting the equipment. Never bypass safety devices or operate the system if you suspect unsafe conditions.
Learn more about the furnace components and operating conditions commonly associated with diagnostic error codes: