Goodman furnace: Ignition Lockout — Flame Not Established After 3 Tries
Try DIY first, then call a pro
What does 1 flash mean on a Goodman furnace? The control tried to light the burners three times without proving flame within 4 seconds of the gas valve opening, then locked out. The code is one short flash followed by a long pause. It auto-resets after 1 hour.
This condition involves the gas or combustion side. If you smell gas or a CO alarm sounds: leave, then call your gas utility. Diagnostic info here is reference — combustion repairs are for licensed technicians.
GOOD NEWS: THE FIRST CHECKS ARE FREE AND TAKE MINUTES.
Try these first — in this order
Clean the flame sensor (15 min) — the highest-success DIY fix. Reset: thermostat OFF for 5–20 seconds, then back ON.
If it keeps locking out after cleaning, gas pressure or burner issues need a licensed tech. DIY part cost: $8–15 / $15–35 — a pro visit for this class of fault typically runs $150–350.
What causes it (in order of likelihood)
- Dirty or oxidized flame sensor (official: coated and/or oxidized) DIY-CHECKABLE
- Bad or misaligned hot-surface igniter DIY-CHECKABLE
- Pressure switch, burner, or gas-pressure problems TECH
Parts referenced by this code
Always match parts against your model's parts list — part numbers vary within a series.
Applies to
GMS8 · GDS8 · GHS8 · GMSS96 · GMH8 · GDH8
Different Goodman generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Goodman GMS8/GDS8/GHS8 Service Manual (RS6612006), p.42 — “one short flash followed by a longer pause”
Verified against Goodman GMSS96 Service Manual, p.32
Last verified 2026-07-06 · how we verify