How Goodman Flash Codes Work
Goodman furnaces use a single amber or green diagnostic LED on the control board. When the furnace is operating normally, the LED stays on solid or blinks slowly once every few seconds. An error code is a rapid flash sequence: a specific number of quick blinks followed by a 3-second pause, then the sequence repeats.
The Goodman flash code system covers 1 through 8 flashes. Each number points to a different fault area. There are no 9-flash or higher codes on standard Goodman residential furnaces.
Goodman also uses two-digit error codes (E1, E2, E3, EE2, EF) that appear on some newer models with seven-segment displays. These codes are covered in the second half of this guide.
Amana furnaces use the same control boards and the same flash codes. Amana is a Goodman brand. If you have an Amana furnace, this guide applies directly.
Complete 1-8 Flash Code Table
| Flashes | Meaning | Most Likely Cause |
|---|---|---|
| 1 | Ignition lockout (3 failed attempts) | Dirty flame sensor |
| 2 | Pressure switch stuck closed (closed when should be open) | Failed switch, water in hose, wiring short |
| 3 | Pressure switch stuck open (open when should be closed) | Blocked vent, cracked hose, failed inducer |
| 4 | High limit switch open | Dirty filter, blocked registers, blower issue |
| 5 | Flame sensed without gas valve call | Stuck gas valve, flame sensor positioned wrong |
| 6 | Polarity or ground fault | Reversed hot/neutral, missing ground |
| 7 | Gas valve circuit fault | Bad valve solenoid, wiring, control board |
| 8 | Blower motor fault | ECM module, capacitor, failed motor bearings |
Most Common Goodman Codes
1 Flash: Ignition Lockout
This is the most common Goodman fault by a wide margin. The furnace tried to ignite three times and failed each time. The board locks out and flashes once.
On a Goodman, the usual suspect is a dirty flame sensor. The flame sensor rod sits in the burner flame and detects that combustion is happening. Over time, a thin coating of combustion residue builds up on the rod. This coating insulates the rod and blocks the microamp signal the control board needs to see.
To fix: Turn off power to the furnace. Locate the flame sensor on the burner assembly. It is a single rod with a ceramic base and one wire attached. Remove the mounting screw. Slide the sensor out. Gently clean the rod with fine emery cloth or a dollar bill. Reinstall and restore power.
A Goodman flame sensor with a clean surface should register 2-7 microamps DC when measured with a multimeter in series. If the sensor is clean but the microamp reading is below 2 microamps, the sensor may need replacement.
2 Flashes: Pressure Switch Stuck Closed
Code 2 means the control board detected that the pressure switch was closed before the inducer motor started. This can happen if the switch contacts are welded shut, if water has bridged the contacts internally, or if the wiring harness has a short to ground.
Test the switch with the furnace off. Disconnect the two wires from the switch terminals. Set your multimeter to continuity. With no vacuum applied, the switch should show no continuity (open circuit). If it shows continuity, the switch is failed and needs replacement.
3 Flashes: Pressure Switch Stuck Open
Code 3 means the pressure switch stayed open after the inducer motor started. This is different from code 2. Here, the inducer runs but the switch does not close.
On Goodman, cracked pressure switch hoses near the inducer housing are a known weak point. The hose rubs against the inducer housing and wears through. Inspect the full length of the silicone hose. Replace it with new hose of the same diameter if you find cracks.
If the hose is intact, check the inducer motor. A failing inducer motor that spins slowly will not create enough draft to close the switch. Check the inducer wheel for debris buildup and the motor for seized bearings.
4 Flashes: High Limit Switch Open
Code 4 means the high limit switch opened because the furnace overheated. This is an airflow problem. Change the filter. Open all supply registers. Check the blower wheel for dirt buildup. Test the blower capacitor.
If code 4 appears immediately after startup (within the first few minutes), the blower is likely the problem. The heat exchanger heats up faster than the blower can carry the heat away. If code 4 appears after 20+ minutes of running, look for a dirty filter or blocked return.
5 Flashes: Flame Sensed Without Gas Valve Call
Code 5 means the control board detected a flame signal when the gas valve was off. This is a safety fault. The board sees a flame where none should exist. The most common causes are a stuck gas valve that leaks gas, or a flame sensor positioned so close to another burner that it picks up radiant heat.
If the gas valve is stuck partially open, gas can flow into the burner box without an ignition command. This is a safety hazard. Turn off the gas at the shutoff valve and call a technician.
6 Flashes: Polarity or Ground Fault
Code 6 means the control board detected a problem with the electrical supply. The incoming 120VAC power has reversed polarity (hot and neutral swapped) or there is no ground connection.
Test the outlet or junction box supplying the furnace. Verify that the black wire is hot, the white wire is neutral, and the green or bare wire is ground. A polarity tester plug is a quick check. Reverse polarity can cause the control board to behave unpredictably and may prevent ignition.
7 Flashes: Gas Valve Circuit Fault
Code 7 means the control board detected an open or short in the gas valve circuit. Measure resistance across the gas valve solenoid terminals. A typical Goodman gas valve reads 20-60 ohms. An open reading (infinite resistance) means the solenoid coil is broken. A very low reading (under 5 ohms) means a short. Either case requires gas valve replacement.
Also check the wiring harness between the control board and the gas valve. Pinched or chewed wires can cause intermittent faults.
8 Flashes: Blower Motor Fault
Code 8 means the blower motor is not operating correctly. On Goodman furnaces with a PSC blower motor, check the run capacitor first. A failed capacitor prevents the motor from starting. On ECM blower motors, the control module may have failed.
Listen for the motor. A humming motor that does not spin usually points to a bad capacitor. A motor that spins but at the wrong speed may have a failing ECM module. A motor that does nothing at all may have a seized bearing or a failed module.
Goodman 2-Digit Error Codes
Some newer Goodman furnaces display two-digit codes on a seven-segment display or through the thermostat interface.
| Code | Meaning | Action |
|---|---|---|
| E1 | Control board internal fault | Replace control board |
| E2 | Watchdog timeout | Check wiring, ground, 24VAC supply |
| E3 | 24VAC / AUX limit circuit open | Check limit switches, rollout switches, wiring |
| EE2 | Invalid control board parameter | Board replacement needed |
| EF | Flame detected with no call for heat | Safety critical, call technician |
E2 and E3 are the most common 2-digit codes. E2 (watchdog timeout) often points to a weak ground connection or loose 24VAC transformer wiring. E3 (limit circuit open) means one of the safety switches in the 24VAC circuit has opened. Check the rollout switches and the high limit switch.
EF (flame detected without call for heat) is the same condition as the 5-flash code on the LED system. Do not ignore this. A gas valve that leaks gas when closed is a fire hazard.
Diagnostic Workflow for Any Goodman Code
Step 1: Read the Code
Open the blower compartment and find the diagnostic LED on the control board. Count the flashes through three full sequences. If your model has a seven-segment display, write down the E-code shown.
Step 2: Power Cycle
Turn the thermostat to OFF. Flip the furnace breaker to OFF. Wait 30 seconds for the control board LED to go dark. Restore power and set the thermostat to call for heat.
Step 3: Follow the Code
Use the code tables above to identify the fault area. Start with the cheapest fix: clean the flame sensor for code 1, check the hose for code 3, change the filter for code 4.
Step 4: Confirm the Fix
Run the furnace through one complete heat cycle after the repair. If the same code returns within that cycle, the root cause has not been fixed. Move to the next likely cause.
Goodman Resetting Procedure
Goodman furnaces do not have a manual reset button on the control board for most codes. A standard power cycle clears the lockout. Turn the breaker off for 30 seconds, restore power, and run a heat cycle.
For code 5 (flame without call) and EF (flame without call on E-code models), the board may require a longer power-off period. Leave the breaker off for 5 minutes to fully discharge the control board capacitors. If the code returns after the extended power-off, the gas valve is leaking and needs professional replacement.
Parts Reference
| Part | Typical Cost | Notes |
|---|---|---|
| Flame sensor (Goodman OEM) | $15-$35 | Clean first before replacing |
| Pressure switch (Goodman OEM) | $20-$50 | Match setpoint to existing part |
| Silicone tubing (1/4” ID) | $5-$15 | Common replacement for cracked hose |
| Limit switch (Goodman OEM) | $15-$40 | Varies by model |
| Gas valve (Goodman OEM) | $100-$250 | Requires gas line work |
| Blower capacitor | $10-$30 | Match µF to existing cap |
| ECM blower module | $200-$500 | Goodman OEM recommended |
| Control board | $150-$350 | Match part number exactly |
When To Call a Professional
Call a technician if you have cleaned the flame sensor, replaced the filter, checked the pressure switch hose, and the code still appears. Codes 5 and 7 (gas valve faults) should always be handled by a professional because they involve gas supply. Code 6 (polarity fault) may require an electrician if the wiring to the furnace is incorrect.
If you smell gas at any point, shut off the gas valve on the supply line, leave the building, and call your gas utility from outside.