Goodman Furnace Code 12
Hard lockoutShown as: 12 flashes, then a pause, repeating
Inducer relay error or improper grounding. The control detected a fault in the relay that runs the induced draft blower, or the furnace is not properly grounded.
Manual wording: “Inducer Relay Fault / Improper Grounding”
Documented for: Goodman GMES80, GCES80 (PCBBF145 control board)
Likely causes, most common first
- Improperly connected inducer
- Bad inducer
- Poor unit ground
- Faulty integrated control module
When to call a technician
Inducer motor, ground wiring and control board work all require a technician.
A Goodman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Instructions - *MES80 / *CES80 Gas Furnace, Category I - IOG-2021H (Daikin Comfort Technologies (Goodman brand), Goodman GMES80, GCES80 80% AFUE gas furnaces (PCBBF145 control board)) · checked 2026-08-25