Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Goodman Furnace Error Codes — Quick Reference
Goodman furnaces signal faults through a flashing LED on the control board. Remove the lower access panel and count the repeating blink sequence. One long flash followed by shorter flashes indicates a two-digit code on newer boards; older boards use a simple count. Goodman shares its control board platform with Amana — the codes are identical across both brands.
| Code | Meaning | Quick Fix |
|---|---|---|
| 1 flash | Lockout — retries exceeded | Manual reset; check igniter and gas |
| 2 flashes | Pressure switch stuck open | Check inducer, hose, drain trap |
| 3 flashes | Pressure switch stuck closed | Inspect pressure switch hose routing |
| 4 flashes | Open high-limit device | Replace filter; check airflow |
| 5 flashes | Flame sensed with no call for heat | Gas valve may be leaking |
| 6 flashes | 115V AC power reversed / bad ground | Check polarity at furnace disconnect |
| 7 flashes | Gas valve energized without call | Gas valve or board fault |
| 8 flashes | Low flame sensor signal | Clean flame sensor rod |
| 9 flashes | Igniter circuit fault | Check igniter continuity; replace if open |
| Continuous | Normal operation (no fault) | — |
| Slow flash | Standby / waiting for call | Normal |
| E1 | Communication fault (some models) | Check thermostat wiring |
| EE2 | EEPROM memory fault | Replace control board |
Technician Tips
Goodman furnaces use a simple LED flash system on the control board. The diagnostic LED is usually visible through the blower compartment window. Count the flashes between pauses — that’s your error code. One flash = normal operation. Two flashes = pressure switch fault. Three flashes = limit switch. Four flashes = flame sensor. Goodman flame sensors are notorious for carbon buildup — cleaning with emery cloth every 2-3 years prevents most lockout calls. The control board on GMS8 and GMSS9 models is particularly sensitive to voltage fluctuations — if you see multiple different codes, check the transformer output (should be 24VAC ±10%).
Prevention: Install a whole-house surge protector on the furnace circuit to prevent board damage from power spikes.
Need Replacement Parts?
Before ordering, match the furnace part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Most Common Codes
1 Flash: Ignition Lockout
The furnace tried to light multiple times and gave up. Start with the flame sensor — a dirty rod is the #1 cause. Remove the sensor (single screw), rub the metal rod with 400-grit sandpaper or steel wool, and reinstall. If that doesn’t work, check the hot-surface igniter for cracks and verify the gas valve opens when the thermostat calls for heat.
2 Flashes: Pressure Switch Stuck Open
The draft inducer motor ran but the pressure switch didn’t see enough negative pressure to close. Check: (1) the rubber pressure switch hose for cracks, (2) the condensate drain trap for blockage on 90%+ models, (3) the inducer wheel for debris. A plugged secondary heat exchanger on high-efficiency models is also common.
4 Flashes: High Limit Open
The heat exchanger overheated and tripped the limit switch. Overwhelmingly caused by a clogged air filter. Replace the filter and allow the furnace to cool before resetting. If the limit trips again with a clean filter, check for blocked supply or return registers and verify the blower wheel isn’t clogged with debris.
5 Flashes: Flame Sensed — No Call for Heat
The flame sensor is detecting a signal even when the thermostat isn’t calling for heat. This usually means a leaking gas valve (allowing gas to seep and ignite on the hot surface of the heat exchanger) or a shorted flame sensor wire. This is a safety issue — shut off the gas supply and call a technician.
6 Flashes: Reversed Polarity / Bad Ground
Goodman furnaces are polarity-sensitive. The hot and neutral wires at the furnace disconnect or outlet must be wired correctly. Swap the two leads at the disconnect if needed. Also verify the unit has a proper earth ground — a missing ground is a common cause of nuisance lockouts.
8 Flashes: Low Flame Sensor Signal
The burner lit, but the microamp signal from the flame sensor is too low for reliable flame proving. Clean the sensor rod first. If cleaning doesn’t raise the signal above ~1.5 µA, the sensor rod may be cracked or positioned incorrectly in the burner flame.
When to Call a Pro
A 5-flash (flame sensed with no call) or 7-flash (gas valve energized unexpectedly) code indicates a potentially dangerous condition — gas valve failure or control board malfunction. Turn off the gas supply and contact a licensed technician before attempting further operation.