Goodman furnace 1 flash: 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. All six emergency signs →
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.
Questions about this code
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.
How do I fix Goodman furnace 1 flash?
Note how often it happens. Flame sensor, igniter, pressure switch, and gas pressure checks are technician work. Avoid repeated resets, and if you smell gas, leave and call the utility from outside.
How much does it cost to fix Goodman furnace 1 flash?
The price depends on the cause. A dirty flame sensor, an igniter problem, and a gas-pressure or burner issue involve different amounts of work, so only a diagnosis can narrow it down.
Related symptoms
These symptoms can appear alongside this code. The link is an association, not a diagnosis, and code meanings vary by brand, model and control.
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 · page updated 2026-10-07 · how we verify
Related Goodman furnace codes
These codes use the same single red led — flash codes system.
| Pattern | Meaning |
|---|---|
| 2 flashes | Pressure Switch Stuck Closed |
| LED off | No LED Signal |
| 3 flashes | Pressure Switch Stuck Open |
| 4 flashes | Open Primary Limit Switch |