Goodman furnace error codes

Per the Goodman service manual, an internal control failure or a blown board fuse will cause the diagnostic LED to provide no signal. It can also simply mean the board isn't getting power.

On Goodman's single-LED control boards, a diagnostic light that stays on without flashing means normal operation. The service manuals list no corrective action for it, so it isn't a fault code. A GMEC96 is different: its service manual lists a solid red LED as a control board internal fault.

The control tried to light the burners three times without proving flame within 4 seconds of the gas valve opening, then locked out. The code is one short flash followed by a long pause. It auto-resets after 1 hour.

The control sees the pressure switch closed while the induced-draft blower is OFF — it waits until the fault clears. Officially: a faulty pressure switch or shorted wiring.

After the induced-draft blower starts, the pressure switch never closes. The control locks out, then auto-resets and retries. Code: three short flashes and a pause.

The high-limit opened — the furnace overheated. The circulator blower runs until the limit closes. Code: four short flashes.

The control detects flame while the gas valve is de-energized. Blowers run continuously as a protection. Official causes: a short to ground in the flame-sense circuit, miswiring, a lingering burner flame, or a slow-closing gas valve.

The flame-rollout control opened — flames left the burner area at some point. The circulator blower is energized full-time. Rollout switches usually need a manual reset, but the cause must be found first.

The furnace keeps running, but the flame sensor's microamp signal has dropped below spec — a warning before ignition lockouts start. Official: coated/oxidized sensor, a badly positioned sensor, or a lazy flame from poor gas pressure.

Official wording: improperly connected igniter, bad igniter, or poor ground to the equipment.

Official: the 115-volt line polarity is reversed or the unit ground is poor. The furnace won't heat until wiring is corrected.

Three failed ignition cycles — the control can't establish measurable combustion and locks out. Same reset as flash models: thermostat OFF 5–20 s, or kill power ≥5 s.

The low-stage pressure switch reads closed while the inducer is off. The control waits until the fault clears. Cause per manual: faulty switch or shorted wiring.

The low-stage pressure switch doesn't close within 5 minutes of the inducer starting → 1-hour lockout, then auto-retry. Official causes: disconnected hose, faulty switch or wiring, blocked venting.

One of three protective limits opened: primary (overheat), auxiliary, or flame rollout. Blowers run until it closes. Official causes: dirty filter or duct restriction, faulty limit, blower issue, blocked flue.

Flame detected while the gas valve is de-energized. Blowers run continuously as protection. Same emergency profile as 5 flashes on flash-code models.

The control detects its onboard fuse open and inhibits all operation except displaying the code. Official probable cause: a short in the low-voltage wiring.

Furnace runs, but the flame-sensor microamp signal fell below spec. Official: coated/oxidized sensor, wrong sensor position, or lazy flame from improper gas pressure.

Official: check for a broken or improperly connected igniter; check for proper ground and correct.

The high-stage pressure switch is stuck closed when high stage is commanded — the furnace runs on LOW stage only regardless of thermostat demand.

High-stage switch won't close. Official checklist: blocked or pinched switch hose, blocked flue and/or intake pipe, blocked drain, weak induced-draft blower, or a failing switch.

115V or 24V power leads are reversed — the furnace refuses to run. Same fix family as the continuous-flash code on flash models.

The control has no shared data set (it drives the variable-speed motor and airflow math). The furnace cannot function until a model-specific memory card loads the data. Display shows ON when accepted.

The control rejected the shared data set — memory cards are model-specific and a card for a different model will be refused.

The control can't detect the ECM blower running when it should be. Official causes: loose/disconnected wiring between motor and control, an open inductor (¾ HP and 1 HP motors), or a failed ECM motor.

The furnace control can't talk to the ECM blower — the furnace won't operate. Causes: loose harness, failed motor, or failed control.

The connected motor's horsepower doesn't match the shared data set — the furnace refuses to run. Fix: correct motor, or correct data via the proper memory card.

The ECM hit a power, speed, or temperature limit and reduced output — the furnace keeps running at reduced airflow. Officially caused by blocked/clogged filters, restrictive or undersized ductwork, blocked inlet, or high ambient heat.

The ECM motor sensed a loss of control or became overloaded and shut down.

The ECM blower motor failed to start 10 times in a row, and the furnace won't operate while the motor can't start. The service manual's probable causes are an obstruction in the blower housing or wheel, seized motor bearings, or a failed blower motor.

The ECM blower motor shut itself down because line voltage was too high (over 140 VAC) or too low (under 70 VAC), or because its power module overheated. The motor restarts once the condition clears, but the furnace can't run while the motor is off. For overheating, the manual names high ambient temperature or heavy motor loading as the likely cause.

The ECM blower motor didn't get all the information it needs to operate, an event kept it from running, or it failed to start 40 times in a row. Probable causes in the manual: an intermittent wiring connection between the control and the motor, a furnace control error, or any of the conditions behind codes b4, b5 and b6.

Indoor airflow fell below the minimum the control calculates from its shared data. The furnace keeps running with the reduced airflow and, if it was on high stage, steps down to low stage to try to recover. It stops if airflow drops to 0 CFM. The manual's probable causes are blocked or clogged filters, blocked or restrictive ductwork, and undersized ductwork.

Normal state. It also confirms the control accepted memory-card data after a board or card procedure.

IdL is the normal idle display on supported Goodman furnaces. The control is powered, waiting for a thermostat call, and ready to receive thermostat inputs. It is not a fault code.

The GMEC96 control is detecting flame current when no flame should be present. This code belongs to the GMEC96 tri-color control; it is not the same as the one-flash ignition-lockout code used by older Goodman boards.

The official GMEC96 wiring legend identifies two red flashes as a pressure switch stuck closed or an inducer error. The switch is reporting draft before the control expects it.

On the GMEC96 control, three red flashes mean the first-stage pressure switch is stuck closed or the inducer circuit is reporting the wrong state. Match the model and the wiring diagram on the blower door before using this definition.

The limit circuit opened because the furnace became too hot or a limit failed. The GMEC96 service manual says repeated limit openings can put the control into a one-hour lockout.

The control detected an open flame-rollout circuit or open fuse. The service manual also explains that an open limit lasting 15 minutes is stored as this five-flash fault.

The pressure-switch signal dropped out often enough during a heat cycle that the GMEC96 control locked the furnace out. This points to an intermittent draft problem rather than a steady switch state.

The furnace exhausted its ignition retries and entered external lockout. The burners did not establish a proven flame within the allowed attempts.

The burners lit, but the control lost flame proof repeatedly and used up its recycle limit. That is different from seven flashes, where ignition never completed successfully.

The GMEC96 wiring legend assigns nine red flashes to improper grounding or reversed 115-volt polarity. The control will not operate correctly until the line wiring is corrected.

The GMEC96 control is detecting gas flow when the thermostat is not calling for heat. The official wiring legend treats this as a separate ten-flash fault, not a normal operating light.

The limit switch circuit has stayed open for more than 5 minutes. The GMEC96 troubleshooting chart lists the symptom as the furnace not operating while the inducer keeps running, and its check step is to reset main power and confirm the indoor blower operates.

The control board's igniter relay is not energizing the hot-surface igniter. The GMEC96 troubleshooting chart gives a single check for this code: replace the control board.

On a GMEC96, a red LED that stays on while the furnace won't run means the control board has found an internal fault. Goodman's troubleshooting chart lists one fix: replace the control board. The code list labels it an internal, gas valve (GV), microprocessor and frequency check error. The control also lights the red LED at power-up while it runs its self-check, before it goes to standby. On older single-LED Goodman boards, a steady light means normal operation, so check your model before relying on this meaning.

A rapid red flash means the GMEC96 control has found a twinning error, and the furnace won't operate. Twinning wires two furnaces of the same model and size together through their TWIN terminals so their blowers run in sync on one duct system. Goodman's chart gives one check for this code: correct the twinning wiring.

Three double red flashes mean the GMEC96's second-stage (high-fire) pressure switch is stuck open or there's an inducer error, and the furnace won't operate. Goodman's chart says to verify the switch and its tubing, and to confirm the inducer is running and pulling enough vacuum to engage the switch. Count the pairs: three double flashes are a different code from three single red flashes (first-stage switch) or six red flashes (pressure switch cycle lockout).

Three amber flashes mean the GMEC96 control is getting a second-stage heat call (W2) without a first-stage call (W1). The control ignores that call, so the furnace won't heat from it. Goodman's chart points to a faulty thermostat, faulty thermostat wiring, or improperly connected thermostat wires. One or two amber flashes are different: they show a normal first- or second-stage heat call.

Four amber flashes mean the GMEC96 control is getting a cooling call (Y or Ylo) without a fan call (G), and the furnace won't operate. Goodman's chart points to a faulty thermostat, faulty thermostat wiring, or improperly connected thermostat wires. In normal cooling the thermostat sends G along with Y or Ylo, and the control shows one or two green flashes.

Rapid amber flashing means the GMEC96 control is reading a low flame sense current. Goodman's troubleshooting chart lists it under a furnace that won't operate and says to check for a dirty or coated flame rod, a poor flame, improper gas pressure, or a poor flame sense wire or connection. The service manual adds that contaminated fuel or combustion air can leave a nearly invisible coating on the flame sensor that weakens the signal.

The modulating control exceeded its allowed ignition retries or flame recycles on a single call for heat and entered Soft Lockout — E0 flashes during the lockout period, then the control retries.

The low-stage pressure switch reads closed at the start of the heating cycle, before the inducer runs.

The low-stage pressure switch (PS1) failed to close within 30 seconds of the inducer starting — the manual's checklist starts with a blocked pressure-switch hose.

The primary high limit opened — insufficient conditioned air is moving over the heat exchanger. Note this differs from GMVC96-generation boards, where E3 covers three limit types.

Flame sensed while the gas valve should be closed — official causes start with a short to ground in the flame-sense circuit or a slow-closing gas valve.

The board's low-voltage fuse is open — almost always a short in the 24V (thermostat) wiring.

Flame-sense microamps dropped below spec — the control has a built-in warning before lockouts begin. Official first cause: coated/oxidized flame sensor.

The control flags the igniter circuit or the equipment ground.

The high-stage switch reads closed at the start of the heating cycle.

PS2 won't close — blocked hose, flue, or drain per the manual. Note: E9 also displays while the control runs its calibration routine; if calibration completes, it clears on its own.

Line-voltage hot/neutral is reversed (or ground is poor) — the furnace refuses to run until corrected.

The inducer drew excessive current or lingered on when it shouldn't — a failing induced-draft motor signature.

The manual-reset flame rollout switch is open, and the furnace won't run. Possible causes listed in the service manual: an orifice plate out of position, a blocked heat exchanger, misaligned burners, or a defective heat exchanger.

The control detects wiring to the furnace that doesn't match the expected configuration — commonly after thermostat or accessory work.

The auxiliary input circuit is open — an external safety device wired into AUX (condensate overflow switch, etc.) has tripped.

The control can't detect the ECM blower running when commanded — loose wiring at the motor or a failed motor.

The control lost communication with the ECM blower — the furnace won't run without it.

The installed motor's horsepower doesn't match the shared data set — usually after a wrong replacement motor or wrong memory card.

The ECM hit an operating limit and reduced output — the furnace keeps running with less airflow. Blocked filters are the manual's first cause.

The blower tripped on overcurrent or lost rotor sync — abnormal motor loading or a sudden change in load.

The blower can't turn — obstruction in the blower housing or a seized motor.

Over/under line voltage to the furnace, or the motor exceeded its temperature limit.

The control failed to deliver a complete parameter set to the ECM — a control-side error.

Delivered airflow is lower than the demand target — blocked filters are the manual's first cause.

The control has no shared data set (NO NET) — the furnace can't run until a model-specific memory card loads it. Display shows ON once data is accepted.

A configuration status code — conventional 1-stage compressor cooling with dehumidification is active. Informational, not a fault.

Configuration status — conventional 2-stage compressor cooling with dehumidification. Informational, not a fault.

The control rejected the memory card — cards are model-specific and a mismatched card will be refused.