Goodman furnace 6 flashes: Rollout switch has tripped

Six flashes means a rollout switch opened. Flame came out of the burner compartment instead of being drawn into the heat exchanger, and this is the most serious routine fault code a furnace produces.

Applies to: Goodman GMS, GMH, GMV8, GMV9 and Amana AMH, AMV9 series gas furnaces with a single red diagnostic LED. On Goodman GMSS9 and Amana AMSS9 this flash count covers the rollout limit being open or the control module fuse being blown — check both on those models.

What it means

Rollout switches sit on or near the burner assembly and open if they detect heat where there should not be any. Their job is to catch flame rollout — flame escaping forward out of the burner box rather than being pulled through the heat exchanger by the draft. Rollout means the combustion path is obstructed or the draft has failed, and it can scorch wiring, damage the furnace, and produce carbon monoxide. Unlike most furnace safeties, rollout switches are manual reset: once tripped they stay tripped until someone physically presses them. That is deliberate. The switch is designed so that a person has to attend the furnace and, in principle, find out why it tripped before it can run again.

Most common causes

A blocked or restricted heat exchanger, so combustion gases cannot pass through it.
A blocked or partly blocked flue, forcing combustion products back toward the burners.
A failed or weak draft inducer that is not pulling flame into the heat exchanger.
A cracked heat exchanger disturbing the combustion airflow.
Burners that are dirty, misaligned, or partly blocked, producing an unstable flame.
Insufficient combustion air in a confined furnace space.
Overfiring, with manifold pressure set too high for the burners.
On models where this code is shared, a blown fuse on the control module rather than a rollout condition.

How to diagnose it

Treat this as a stop-and-call fault rather than something to work through. The list of causes is dominated by conditions that produce carbon monoxide.
Check that carbon monoxide alarms in the house are present and working. If any has sounded, leave and call the fire service from outside.
Look for visible scorching, soot, or melted wire insulation around the burner compartment — but from outside, without dismantling anything.
Note whether the flue or vent termination is obviously blocked.
On GMSS9 and AMSS9 models, be aware this code also covers a blown control fuse, which is a much less alarming cause. A technician will distinguish them quickly; you cannot from the flash count alone.

How to fix it

Turn the furnace off at its service switch and leave it off. Call a licensed heating technician.
Do not press the rollout switch reset buttons to restart the furnace. The switch tripped because flame went somewhere it should not, and resetting it without finding out why puts the furnace straight back into that condition.
Have working carbon monoxide alarms on every level of the home and outside each separate sleeping area, which is what NFPA 720 and US Consumer Product Safety Commission guidance call for. That includes the level the furnace is on — basements, attics and utility spaces are where a combustion fault starts, and an alarm only on bedroom floors can miss it for a long time. This fault is one of the situations those alarms exist for.
Every underlying cause on the list — heat exchanger, flue, inducer, burners, gas pressure — is licensed work. There is no homeowner portion of this repair.

Notes

The manual reset on rollout switches is the clearest signal a furnace gives about how seriously to take a fault. Every other common safety resets itself. This one requires a person, precisely so the condition gets investigated rather than cycled through.

All codes for this manufacturer

Goodman and Amana furnace fault codes — every code, with what differs between models.

Not sure this is your brand?

The same count means something else on other furnaces. What 6 flashes means on every brand puts them side by side.

This code is not a homeowner repair. Faults in this group involve the gas valve, the burner compartment, or the heat exchanger — the parts whose failure can put combustion products, including carbon monoxide, into the air the house breathes. Do not reset it repeatedly to keep the heat on. Have it looked at by a licensed technician, and make sure there is a working carbon monoxide alarm on every level of the home, including the level the furnace is on.

Sources

Goodman Manufacturing — Diagnostic Code Identification System (model-specific fault code lookup)

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.