How do you fix Goodman flash?

Restore the gas supply if that is the cause — reopen a valve that was closed, or refill the tank. Replace the air filter and confirm supply registers are open. Restricted airflow does not cause this directly but it accompanies enough other faults to be worth eliminating first. Full steps and safety notes are on this page.

Goodman furnace 1 flash: Lockout after too many failed ignition attempts

One flash means the furnace tried to light, failed, tried again, and has now stopped trying. It is a lockout, not a single failure — the control has already made every attempt it is allowed.

Do the simple checks below, then stop. The simple checks listed above are genuinely homeowner work and worth doing first. Beyond them, this fault involves 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. If the simple checks do not resolve it, stop there and call a licensed technician rather than resetting the furnace repeatedly to keep the heat on. Make sure there is a working carbon monoxide alarm on every level of the home, including the level the furnace is on. The conditions that mean stop now.

Applies to: Goodman GMS, GMP, GMH, GMV8, GMV9 and Amana AMH, AMV9, AMSS9 series gas furnaces with a single red diagnostic LED. Later communicating boards show this condition as code E0 instead.

What it means

The control gives the furnace a fixed number of ignition attempts, normally three, and counts each one that does not end with a proven flame. When the count runs out it stops calling for gas and reports the lockout. That distinction matters when reading the code: the furnace is not failing to light right now, it failed repeatedly a short time ago and has taken itself out of service deliberately. Most controls clear the lockout automatically after about an hour and try again, which is why a furnace with this fault often appears to work for one cycle and then quit — it is not recovering, it is retrying on a timer. The underlying cause is almost always either no gas reaching the burners, no ignition source, or a flame that lit but was not detected.

Most common causes

The gas supply is off or interrupted — a closed manual valve, an empty propane tank, or a utility outage.
The hot surface igniter has failed or cracked, so nothing is lighting the gas.
The flame sensor is coated with oxide, so the flame lights and the control cannot see it and shuts the gas off.
The flame sensor is bent out of the flame path, with the same result.
The gas valve is not opening, or the manifold pressure is too low to establish a stable flame.
Poor electrical grounding, which prevents the flame rectification signal from being read even when everything else is correct.
A blocked or partly blocked flue restricting combustion enough that the flame will not stabilise.

How to diagnose it

Confirm the code by counting the flashes through the sight glass, waiting for the pause, and counting again. A miscount sends you to the wrong fault entirely.
Check that other gas appliances in the house are working. If nothing gas-fired works, the problem is the gas supply and not the furnace.
Check the furnace's own shutoff valve is open and, on propane, that the tank is not empty.
Watch a full cycle through the sight glass if you can do so with the panel in place. Whether the burners light at all separates an ignition problem from a flame-sensing problem — if they light and go out after a few seconds, the flame is being lost rather than never made.
Reset by switching the furnace off at its service switch for about thirty seconds, then on, and watch one complete attempt.

How to fix it

Restore the gas supply if that is the cause — reopen a valve that was closed, or refill the tank.
Replace the air filter and confirm supply registers are open. Restricted airflow does not cause this directly but it accompanies enough other faults to be worth eliminating first.
Everything else on this list belongs to a technician. Cleaning a flame sensor, replacing an igniter, testing manifold pressure, and checking the gas valve all involve the flame-sensing circuit, the gas train, or both.
Do not repeatedly reset the furnace to force it to run. Each reset starts another sequence that delivers gas to a burner that may not light it, and repeated unburned gas cycles are exactly what the lockout exists to stop.

Notes

A furnace that lights, runs a few seconds, then shuts off and eventually locks out is the classic dirty flame sensor. It is one of the most common causes of this code and one of the cheapest repairs, but it sits in the flame-sensing circuit, which is a licensed technician's work.

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 1 flash means on every brand puts them side by side.

Models this code appears on

From the manufacturer's per-model database. If your model is not listed, this code may not exist on your board, or it may mean something different — check the model page.

This lockout across three Goodman generations and beyond

Goodman has expressed this exact event three ways as its boards evolved: one flash on these single-LED models, seven red flashes on the GMEC96's three-colour LED, and E0 on the communicating text displays — same lockout, three dialects. Other brands agree on the event if not the number: Carrier code 14 is ignition lockout, and Allied's five flashes the Watchguard version of retries exceeded. If you replace one of these older furnaces someday, the fault will follow you under a new name.

What the fix costs

On furnaces of this generation the usual suspect is the hot surface ignitor, and the ignitor cost guide has the numbers: $150–350 installed on a standard visit, $250–500 after hours, for a part that runs $20–60 universal or $40–120 OEM. One detail from that guide earns its keep on older models specifically: replacement is the moment to specify silicon nitride rather than the older spiral carbide element, because it lasts years longer for similar money. If diagnosis lands elsewhere — weak gas supply, flame-proving trouble — the flame sensor cleaning alternative is $80–200, which is why the $75–150 diagnostic beats parts-guessing even on a furnace this age.

DIY or call a pro?

A single reset after a suspicious one-off is fair; a reset routine is not, because every spent attempt cycles raw gas through a heat exchanger that, on furnaces this old, deserves gentler treatment. The ignitor swap itself is the industry's most argued-about DIY — two screws and a plug on many models — but the honest gate is the diagnosis, not the dexterity: one flash cannot tell you the ignitor failed rather than the gas valve or flame sensing, and working next to the gas train on a guess is where this site draws the line. Have the fault named professionally; then, if it is the ignitor and you proceed yourself, never touch the new element's ceramic with bare fingers.

What this looks like

From the outside, this usually shows up as the furnace turns over but never lights — that walkthrough covers what to check in order, and when it stops being a homeowner job.

Sources

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.