Furnace Fault Codes

Goodman furnace 8 flashes: Igniter circuit fault, most often caused by poor grounding

Eight flashes indicates an igniter relay fault or a shorted hot surface igniter. Goodman's own service bulletin reports that in the field it is most often caused by an open or insufficient furnace ground.

Applies to: Goodman GMH, GDH, GCH and Amana AMH series gas furnaces, and later models including GMSS9 and AMSS9 where it is described as a problem with the igniter circuit. Goodman documented this code as missing from the wiring labels and service manuals of some early H-model furnaces.

What it means

The nominal meaning of this code, from the control manufacturer, is a fault in the igniter relay circuit or a shorted hot surface igniter. What makes it worth a page of its own is what Goodman found afterwards. In service bulletin SF-024 the company documented that field reports linked this code most commonly not to the igniter at all, but to an open or insufficient ground at the furnace — and that the code was missing entirely from the wiring labels and service manuals of some H-model furnaces, so technicians were meeting a flash count with no published meaning. That makes grounding the first thing to check rather than the last, which inverts the obvious reading of the code.

Most common causes

How to diagnose it

  1. Confirm the count is eight and not seven, since the two point at different circuits.
  2. Note whether the igniter glows at all during a start attempt, if you can see it through the sight glass without opening anything.
  3. Mention recent electrical work, a control board replacement, or a blower motor replacement to the technician. Each disturbs a ground connection this fault depends on.
  4. On an older H-model furnace, be aware the code may not appear on the label inside the access panel at all. Its absence there does not mean you have miscounted.

How to fix it

  1. The published remedy is to check and tighten every ground wire connection to the furnace chassis, with particular attention to the blower motor ground and the low voltage common ground.
  2. After grounds are secured, power the furnace off for about ten seconds and back on to clear stored fault codes.
  3. If the code returns after the grounds are corrected, the igniter is replaced.
  4. This work is inside the cabinet, on the ignition circuit, and is a technician's job. The useful thing a homeowner can do is tell the technician the code is eight flashes and that Goodman associates it with grounding, which can save a wasted igniter.

Notes

This is a good illustration of why a code's book meaning and its field meaning can differ. Read literally, eight flashes sends you to buy an igniter. Goodman's own bulletin says to check the grounds first, and that the igniter is the second move rather than the first.

Related

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 8 flashes 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.

Which brands split this pair, and which do not

Goodman is not alone in fusing igniter and ground into one number — Trane's nine flashes makes the identical conflation, for the identical reason: from the control's seat, a dead igniter and a broken ground reference can look the same. The comparison that illuminates is with boards that split them: Goodman's own GMEC96 gives the relay its private code at twelve red flashes, and York's twelve red names the open hot surface igniter outright. The igniter code hub maps the whole split-versus-fused landscape across brands.

What the fix costs

Price the possibilities in the order the service bulletin's field data ranks them. Grounding — the bulletin's most common culprit — is wiring labour on a $75–150 diagnostic, often the cheapest outcome on the page. The igniter itself is $150–350 installed for a $20–120 element per the ignitor cost guide. The board's relay is the dear end at $400–900. The trap this code sets is buying those in reverse: an igniter or board sold on the flash count alone, against a fault where the manufacturer's own bulletin says the wiring usually did it, has real odds of being money spent to change nothing. The ground check costs minutes; insist it happens first.

DIY or call a pro?

Professional throughout — every branch of this code is electrical, and the deciding measurements (igniter resistance, ground integrity, relay output) are meter work near the gas train. The homeowner's leverage is context and sequence. Context: recent electrical work anywhere in the house, or a history of companion codes like weak flame signal, both argue for the grounding branch, and saying so shapes the visit. Sequence: ask explicitly for ground-before-parts, citing the bulletin this page does. And if eight flashes arrived immediately after an installation or a board swap, route the call to whoever did that work — a missing chassis ground on day one is their line item, not yours.

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.