Goodman GMVM970803BN 80,000 BTU 97% AFUE Modulating Gas Furnace with Variable-Speed ECM Blower 11-FLASH Error Fix: Communication Error — ComfortNet Bus

Error code 11-FLASH on the Goodman GMVM970803BN 80,000 BTU 97% AFUE Modulating Gas Furnace with Variable-Speed ECM Blower means: Communication Error — ComfortNet Bus. Communication failure between the furnace control board and the ComfortNet communicating thermostat or other system components on the communication bus — check thermostat wiring, verify ComfortNet compatibility, and check for electrical interference on the communication lines; only applies to systems with ComfortNet communicating thermostats

The most successful fix is "Test and Replace Faulty ComfortNet Communication Wiring or Components" (medium difficulty, ~45 minutes). Estimated DIY cost: $10-$20. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Test and Replace Faulty ComfortNet Communication Wiring or Components") is rated medium difficulty and takes about 45 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Wire strippers, Wire cutters.

DIY cost: $10-$20. Professional repair typically costs $120-$180. Many homeowners save money by trying the top-ranked community fix first.

The Goodman GMVM970803BN 80,000 BTU 97% AFUE Modulating Gas Furnace with Variable-Speed ECM Blower has 8 other known error codes, including: 10-FLASH (Incorrect Blower Speed / DIP Switch Configuration), 12-FLASH (Blower Motor Fault (ECM)), 13-FLASH (Outdoor Ambient Sensor Fault), 1-FLASH (System Lockout — Retry Limit Exceeded), 2-FLASH (Pressure Switch Stuck Closed), and 3 more.