Goodman Furnace Code 5
Safety faultShown as: 5 flashes, then a pause, repeating
Flame sensed when there should be none. The control detected flame for more than about 4 seconds with the gas valve de-energized. The furnace shuts down and both blowers keep running.
Manual wording: “Flame Sensed>4.25 Seconds with Gas Valve De-Energized”
Documented for: Goodman GMS8, GMH8, GDS8, GDH8, GHS8, GME8, GMES80, GCES80, GMSS92, GMSS96, GCSS96 (single red diagnostic LED)
Likely causes, most common first
- Short to ground in the flame sense circuit
- Lingering burner flame
- Slow closing gas valve
What you can safely check yourself
- Turn the furnace off at its power switch and leave it off until a technician arrives
When to call a technician
A gas valve that may be leaking through, or a flame that will not go out, is an immediate technician call. Shut the furnace off and do not attempt any test yourself.
A Goodman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation Instructions for *M(H,S)8 / *D(H,S)8 / *HS8 / GME8 Gas Furnace (Category I) - IO-359J (Daikin Comfort Technologies (Goodman brand), Goodman GMS8, GMH8, GDS8, GDH8, GHS8, GME8 80% AFUE gas furnaces) · checked 2026-08-25
- 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
- Installation Instructions for *MSS9* & *CSS9* Single-Stage Gas Furnace - IOG-2009Q (Daikin Comfort Technologies (Goodman brand), Goodman GMSS92, GMSS96, GCSS96 single-stage 92/96% AFUE gas furnaces) · checked 2026-08-25