Answer first: Count the flashes between the long pauses — that count is the code. But the count only means something once you know which control board you have. Goodman has used several different code systems, and the same number of flashes can mean different things on different boards: for example, 3 flashes means “pressure switch stuck open” on the common single-stage board, but on Goodman’s packaged gas/electric units the same family of manuals assigns 3 flashes to a pressure switch stuck closed. Find your board family in the charts below before you interpret anything — and if your model family is not listed, do not guess from another family’s chart.
Who this applies to
Goodman gas furnaces with a red diagnostic LED on the integrated control board, in three broad groups:
- Single-stage furnaces with one red LED (many 80% and 90%+ models, e.g. the GME8/GMH8/GMS8-era boards) — Chart 1.
- Two-stage 96% furnaces with red, amber and green LEDs (e.g. GMEC96, GCEC96, GMVC96-type boards) — use the red LED column in Chart 2.
- Newest single-stage furnaces with a digital display (e.g. GM9S92, GM9S96, GC9S96) — these do not use blink counts at all; see the display section after the charts.
If your furnace is a packaged outdoor unit, a heat pump, or an air handler, do not use these charts — Goodman assigns different meanings there.
How to read the code safely
- Look through the small observation window in the blower access door if your model has one. Goodman’s own manuals describe the light as viewable through that window. Do not open the cabinet or remove any door or panel to find the light. If you cannot see a light without opening the unit, stop and call a professional.
- Count the flashes in one group, then wait for the longer pause. The group repeats — count twice to be sure.
- Write down: the flash count, whether the pattern is steady, rapid, or grouped (some two-stage boards use “double flashes”), and what the furnace was doing (fan running? inducer running? no heat?).
- Note your model number from your paperwork or manual before using any chart row (see the accuracy section below).
- Never press buttons on the control board, move wires, or jump/remove any switch to “test” a code. Reading the light is the only step here.
Chart 1 — Single red LED, single-stage furnaces
Source: diagnostic legend printed with the wiring diagram in Goodman’s Installation Instructions for the GME8/AMEH8 family (the same legend is used across the related (A/G)MH8, GDH8 and ADSH8 models). Meanings below are the manual’s own wording, in plain English.
| Flash count / pattern | What it means (plain English) | Safe owner check | Call a pro when… |
|---|---|---|---|
| Steady on | Normal operation — the board is powered and no fault is stored | None needed if the house is heating normally | The light is steady but there is no heat after the checks in Article 1 |
| Off (no light at all) | Control failure — the board has no power or has failed internally | Look (do not touch) at the breaker panel: is the furnace breaker tripped? Check the thermostat display is alive | The breaker is fine, or trips again — do not keep resetting it |
| Rapid flashes | Reversed 115-volt polarity / verify ground — a wiring or grounding problem at installation level | None — this is not an owner fix | Immediately; this is an electrical fault |
| 1 flash | System lockout — the furnace tried and failed to light, ran out of retries, and shut down for safety | Thermostat set to Heat, fan on AUTO, setpoint above room temperature; filter not clogged; then one restart only, the way your manual describes (thermostat call off, or power off and back on at the switch/breaker) | Lockout returns even once, or you smell gas at any point — stop, no more restarts |
| 2 flashes | Pressure switch stuck closed — the switch that proves safe venting reads “closed” when it should be open | None inside the unit; confirm thermostat is not calling for heat and note whether the pattern appears at start-up | Always — proving this needs internal testing |
| 3 flashes | Pressure switch stuck open — the venting-proving switch never closes, so the furnace will not fire | From outside the unit only: make sure nothing is blocking the vent/intake termination outdoors (snow, leaves, stored items) | The termination is clear, or the code repeats — do not open the unit to reach the switch or its tubing |
| 4 flashes | Open high limit — the furnace overheated and a temperature safety switch opened | This is the airflow code: replace a dirty filter, open all supply vents and returns, make sure returns are not blocked by furniture | The code returns after filter/vents are fixed, or the blower is not moving air — repeated limit trips are a pro diagnosis |
| 5 flashes | Flame sensed without the gas valve — the board “sees” a flame when none should be there | None | Always, and promptly — this is a gas-valve/flame-sensing fault, not an owner check |
| 6 flashes | Open rollout or open fuse — a flame-rollout safety switch has opened, or the board fuse is open | None. Do not look for or reset a rollout switch yourself | Always, immediately — rollout faults are a fire-safety event; keep the furnace off until checked |
| 7 flashes | Low flame signal — the flame sensor’s signal is weak (coated sensor or weak flame are typical causes a technician tests for) | None — flame-sensor cleaning is internal work, not an owner check on this site | Always; if it follows a lockout (1 flash), treat it as the same call |
| 8 flashes | Check igniter or improper ground — the igniter circuit or grounding needs testing | None | Always — igniter handling and ground testing are pro work |
Chart 2 — Two-stage 96% furnaces, red LED (with amber and green LEDs on the board)
Sources: Goodman’s Installation Instructions troubleshooting chart for the *CEC96 two-stage furnaces and the red-LED legend in the *MEC96 technical/service documentation (Service Instructions RS6612013). Only the red LED is charted here — on these boards the amber and green LEDs report stage/status information, which is a common reason generic charts confuse people.
| Flash count / pattern (red LED) | What it means (plain English) | Safe owner check | Call a pro when… |
|---|---|---|---|
| 1 flash | Flame sensed when no flame should be present | None | Always, promptly — gas-valve/flame-sensing fault |
| 2 flashes | Pressure switch stuck closed / inducer error | None inside the unit | Always — internal testing required |
| 3 flashes | First-stage pressure switch stuck open — low-fire venting could not be proven | Outdoors only: vent/intake termination not blocked by snow, leaves or stored items | Termination is clear or the code repeats |
| 4 flashes | Open limit circuit — main limit, auxiliary limit, or rollout switch is open | Airflow first: replace a dirty filter, open all vents and returns, unblock returns | Code returns after airflow is fixed, or a rollout is involved — keep the furnace off for rollout symptoms (scorch marks, burnt smell) |
| 5 flashes | Limit and rollout circuit open for 15 minutes; open control-board fuse or rollout switch | None | Always — a timed-out safety circuit is not an owner reset |
| 6 flashes | Pressure switch cycling lockout — the pressure switch opened 5 times during one heating cycle | Outdoors only: vent termination clear | Always if it repeats — venting/inducer diagnosis is pro work |
| 7 flashes | External lockout (retries) — repeated attempts to light have failed and the control has locked out | Thermostat Heat/AUTO and setpoint; filter condition; then one restart only, as your manual describes | Lockout returns even once, or any gas smell — stop |
| 9 flashes | Improper grounding or reversed polarity | None — not an owner fix | Immediately; electrical fault |
| 10 flashes | Gas valve current detected with no call for heat | None | Always, promptly — gas-valve/control fault |
| 11 flashes | Open limit switch circuit for more than 5 minutes (inducer running) | Airflow checks as for 4 flashes, once | Code persists or repeats — prolonged limit opening needs a technician |
| Rapid flash | Twinning error — applies only when two furnaces are twinned together | None | Always; single-furnace homes should never see this — if you do, the board/wiring needs a technician |
| Three double flashes | Second-stage pressure switch stuck open — high-fire venting could not be proven | Outdoors only: vent termination clear | Always if it repeats |
Newest furnaces: if your Goodman shows letters/numbers on a display instead
The current single-stage families (Goodman GM9S92, GM9S96, GC9S96 and the matching Amana models) replaced blink counting with a small digital display on the board plus a stored-fault menu. If yours has a display, do not try to convert what you see into a blink chart — copy the exact characters shown and match them in the troubleshooting chart of the official service manual for those models (RS6612022, listed in Sources). The faults that manual’s chart covers include:
- Lockout after too many ignition retries; failure to establish flame; loss of flame after it lit
- Pressure switch circuit closed at the start of the cycle, or failing to close (the manual lists a blocked/pinched hose, blocked flue or inlet piping, and a weak induced-draft blower among the causes a technician checks)
- Primary limit circuit open (the manual lists blocked filters and ductwork among the causes — the one item on this list with a genuine owner check: your filter and vents)
- Flame sensed with no call for heat; open rollout switch; open igniter; low flame-sense signal
- Open board fuse or a short in the low-voltage wiring; no power to the control; reversed polarity or poor ground
- Gas-valve and internal control-board faults
Every item above except filter/vents is technician diagnosis. The display exists so you can report the exact code to the technician, which shortens the visit.
The safe owner checks that recur across almost every code
Do these, in this order, before you call — and only these:
- Thermostat: set to Heat, fan on AUTO, setpoint a few degrees above room temperature. Replace dead thermostat batteries if it has them.
- Filter: check it; if it is visibly clogged, replace it with the correct size and airflow direction. A dirty filter is the most common owner-side cause behind limit (overheating) codes — Goodman’s service manual for the current furnaces calls dirty filters the most common cause of inadequate heating or cooling performance.
- Vents and returns: open every supply vent; clear anything blocking return grilles.
- Breaker: look at the panel once. If the furnace breaker is tripped, that is information for the technician — a breaker that trips again is a stop sign, not a reset routine.
- Outdoor vent termination (from outside only): on high-efficiency furnaces, confirm the intake/exhaust pipes are not buried in snow or blocked by leaves or stored items.
- One normal restart, only for a lockout code, and only the way your manual describes it (ending the thermostat call, or switching power off and back on at the furnace switch/breaker). If the same code comes back, you are done — no second attempt.
For the full step-by-step version of these checks on the most common symptom, see Furnace Blower Runs But No Heat: What to Check, In Order.
Why online Goodman charts disagree — read this before trusting any chart (including this one)
- Goodman changed the code system more than once. Single-LED boards, three-LED two-stage boards, and display boards assign different meanings to similar-looking signals. A chart copied from one board and pasted under a general “Goodman codes” headline will be wrong for the other boards.
- Even Goodman disagrees with “Goodman.” In Goodman’s own manuals for its packaged gas/electric units, 2 flashes means a pressure switch stuck open and 3 flashes a pressure switch stuck closed — the reverse of Chart 1 above. Those units are not furnaces, but the example proves why the model family, not the brand name, decides the meaning.
- Copied charts drift. Third-party pages copy each other, drop the model list, and keep meanings after boards are revised. That is why every row above is tied to a named Goodman document in Sources.
Find your model number before you use a row: use the paperwork left with the furnace, the homeowner manual, or the model printed in your installation documents. Goodman’s manuals state the model and manufacturing numbers are the positive identification for the unit and should be used when requesting service or parts. If you cannot match your model to a chart family here, treat the flash count as a note for your technician — not as a diagnosis.
What it is likely to cost, and the sensible next step
A blink code narrows the search; it does not name the failed part, so do not let anyone quote a repair from the code alone. The normal path is a diagnostic visit, then a priced repair. Planning ranges below are the same verified US national ranges used across this site (last checked November 14, 2026):
| Item | US range (parts + labour unless noted) |
|---|---|
| Diagnostic / service call | $75–$200 |
| Replacement air filter, owner-supplied (part only) | $5–$30 |
| Igniter replacement by a pro | $150–$400 |
| Flame-sensor service/replacement by a pro | $100–$300 (cleaning $75–$150) |
| Pressure-switch replacement by a pro | $150–$350 |
| Control-board replacement by a pro | $300–$900 |
- When you call, give the technician: the flash count/pattern, your model number, and what the furnace was doing (blower running? inducer running? no heat at all?). That combination is what the code system is for.
- If the quote is large and the furnace is old, compare repair against replacement before authorising the work.
- Browse the rest of the furnace guides from the Furnaces hub.
Stop — call a professional now if any of these apply
- You smell gas, or a carbon-monoxide alarm sounds — leave the house and call your gas utility or emergency services first, a technician second.
- You see scorch marks, smell burning, or the code points to rollout (Chart 1: 6 flashes; Chart 2: limit/rollout rows).
- The breaker trips more than once, or the code is an electrical one (rapid flashes, Chart 2: 9 flashes).
- A lockout code returns after one manual-described restart.
- Any code comes back a second time after the safe checks above.
- You would have to open the cabinet to see or reach anything. That is the line between reading a code and servicing a furnace — stay on the reading side.
Sources
Every chart row above comes from Goodman’s own documentation for the named model families — not from third-party code charts.
- Goodman (Daikin Comfort Technologies), Service and Troubleshooting — GM9S92 / GM9S96 / GC9S96 / AM9S92 / AM9S96 / AC9S96 / VM9S96 / VC9S96, Single Stage Gas Furnaces and Accessories, RS6612022 Rev. 3 (status and troubleshooting charts; filter guidance; model nomenclature): https://mobile.goodmanmfg.com/mobileapp/stellent/pdf/infoPdf/Lit/RS6612022R3.pdf
- Goodman Manufacturing, Technical Manual — AMV9/ACV9 40″ 90% Gas Furnace Units, RT6612008 Rev. 3 (self-diagnosing control module; LED viewed through the observation window in the blower access door): https://mobile.goodmanmfg.com/mobileapp/stellent/pdf/infoPdf/Lit/RT6612008r3.pdf
- Goodman Manufacturing, Installation Instructions — GME8/AMEH8 (and related (A/G)MH8, GDH8, ADSH8), wiring-diagram diagnostic LED legend (Chart 1).
- Goodman Manufacturing, Installation Instructions — *CEC96 Two-Stage Gas Furnaces, Troubleshooting Chart (Chart 2); and Service Instructions RS6612013 — GMEC96/AMEC96 Two-Stage Furnaces, red-LED legend (Chart 2).
- Current literature for every model is published by the manufacturer at https://www.goodmanmfg.com — match the document to your exact model number before relying on a row.
Last checked: November 14, 2026