7 flashesGoodman, Amana · GMSS9 / GCSS9 · Furnace

Goodman, Amana GMSS9 / GCSS9 error code 7 flashes

Flame sense signal low

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.

Amana AMSS9 / ACSS9

Needs attention soon

Also written as 7 blinks

Which models this applies to. Applies to GMV8 / GMV9, GCH / GDH / GME / GMH, and GDS / GHS / GMS / GKS. GMN, GMP and GMT stop at five flashes, so those units can never report a 7.

Quick answer

On Goodman GMSS9 / GCSS9 (2000s), 7 flashes is a fault. It means flame sense signal low. A first thing to check: Flame sensor dirty, corroded, or mounted at the wrong distance from the flame.

Applies to: Goodman GMSS9 / GCSS9; Goodman and Amana GMSS9, GCSS9, AMSS9, ACSS9 flash codes · Furnace · 2000s
Type of code: Fault; Urgency: Needs attention soon
First safe check: Look at the flame pattern with the burner running. It should be steady and roughly straight, not leaning, fluttering or lifting off the port.

Checked 2026-09-26

What 7 flashes means on this model

The burner lit, but the flame sensor was not reading a steady flame. The control saw the flame flicker, drop out, or come on too weakly, and shut down rather than run with an unstable flame. An unstable flame is an incomplete burn, and incomplete burn is how carbon monoxide gets made.

Symptoms you will notice

Furnace starts, runs unevenly, then stops
Long delay between the blower starting and heat at the vents
Burner sounds rough or unsteady
Furnace may restart on its own after a pause

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 dirty, corroded, or mounted at the wrong distance from the flame
Flame sensor wiring loose or a poor ground at the burner box
Dirty burner ports or a burner assembly that has shifted out of position
Wrong burner orifice or a gas pressure problem producing a lazy flame
Failing flame sensor that reads erratically

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 flame pattern with the burner running. It should be steady and roughly straight, not leaning, fluttering or lifting off the port.
Clean the flame sensor rod with fine steel wool. Do not use sandpaper.
Check that the burner assembly is seated and the sensor bracket is not bent.

Do not do these

×Do not adjust the gas pressure or change orifices yourself.
×Do not bypass the flame sensor to keep the burner running.
×Do not run the furnace if the flame looks yellow or orange rather than blue. Yellow means incomplete combustion.

When to call a technician

Book a technician, do not keep resetting it

This fault will not clear on its own. Every power cycle gives the control one more failed attempt, and repeated attempts are what turn a cheap part replacement into a seized or contaminated system.

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.

Sensor cleaning and replacement is fine homeowner work. Anything touching gas pressure is not.

What it costs to fix

Parts

Flame sensor $20 to $60. Orifice kit $20 to $60. Gas valve $150 to $400.

Labor

One to two hours for a sensor or orifice set.

DIY or technician