Goodman, Amana GMSS9 / GCSS9 error code 1 flash
Furnace lockout after 3 ignition retries
Goodman is the platform name, and your unit may not say it
Amana AMSS9 / ACSS9 is the same board with a different badge, so this page covers all of them. The fault, the checks and the parts are identical, which is why there is one page rather than one per brand.
Quick answer
On Goodman GMSS9 / GCSS9 (2000s), 1 flash is a fault. It means furnace lockout after 3 ignition retries. A first thing to check: Flame sensor reading dirty or weak.
- Applies to
- Goodman GMSS9 / GCSS9
- Goodman and Amana GMSS9, GCSS9, AMSS9, ACSS9 flash codes · Furnace · 2000s
- Type of code
- Fault
- Urgency: Stop using it
- First safe check
- Look at the igniter through the burner assembly opening. A working hot surface igniter glows bright orange or white. A cold one is the usual suspect.
What 1 flash means on this model
The control counted three failed ignition attempts and shut the burner down. It is the same lockout the older flash-count boards reported as one flash, carried over to a platform that counts attempts internally rather than announcing each one.
Symptoms you will notice
- Furnace will not fire at all
- Blower runs for a few seconds, then stops
- No heat at any thermostat setting
- Code comes back as soon as you reset it
Common causes
The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:
- Flame sensor reading dirty or weak
- Hot surface igniter not reaching temperature
- Gas valve not opening fully, or not opening at all
- Supply valve shut, or gas service not active
- Loose or corroded wire at the valve, igniter or sensor
- Failed inducer motor, which sometimes presents as an ignition fault
- Cracked heat exchanger, which on these furnaces is a replace-the-unit finding
What you can safely check
These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.
- Look at the igniter through the burner assembly opening. A working hot surface igniter glows bright orange or white. A cold one is the usual suspect.
- Follow the gas line back to the meter. The handle sits parallel with the pipe when gas is on.
- Check the breaker and any wall switch nearby.
- Run another gas appliance to confirm service is actually flowing.
- Wipe the flame sensor rod with fine steel wool or a clean cloth. Do not use sandpaper; it leaves grit that makes it fail again.
Do not do these
- ×Do not keep resetting. The control counts attempts, and once it trips into a timed lockout it may sit there for an hour before it will try again.
- ×Do not jumper the flame sensor or any other switch to force a run.
- ×Do not light the burner by hand with a lighter. The rollout and high limit switches are what stop combustion gases from reaching the rest of the house.
When to call a technician
Stop using the appliance and call today
This one is a safety limit, not a nuisance. The control is shutting the unit down to prevent damage or a hazard, and it will keep doing that until the underlying cause is fixed. Running it anyway risks the expensive failure it was designed to prevent.
- This is a fuel-burning appliance, so treat anything involving a burner, gas valve or flue as technician work. If you smell gas at any point, leave the property and call the gas utility from outside rather than continuing to diagnose.
- If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.
Cleaning and replacing a flame sensor is a reasonable homeowner job with a screwdriver. A gas valve is not.
What it costs to fix
Parts
Flame sensor $20 to $60. Hot surface igniter $40 to $90. Gas valve $150 to $400. Contactor or capacitor under $60.
Labor
One to two hours for a sensor or igniter. Budget more if the valve is involved, since it is a sealed gas connection.
DIY or technician
Cleaning and replacing a flame sensor is a reasonable homeowner job with a screwdriver. A gas valve is not.
Typical US part and labor ranges, 2026. They vary by region, model and contractor, so treat them as a planning figure, not a quote.
Scope of this code
- Code table
- Goodman and Amana GMSS9, GCSS9, AMSS9, ACSS9 flash codes
- Models in scope
- Goodman GMSS9 / GCSS9, 2000s
- Checked
- Confirm on your own unit
- Find the model number on the data plate, then check this code in the service manual for that model. Manufacturers revise code tables between model years, and a revised board can renumber a fault.