Igniter
Price the ignition part only after confirming the model number and connector.
Goodman 8 Flash Error Code — What It Means
Eight flashes on a Goodman furnace diagnostic LED indicates an ignition failure lockout. The control board attempted to light the burners (up to three tries, depending on model) and the flame sensor never confirmed a stable flame. After exhausting its retry attempts, the board locks out and flashes code 8 until the fault is manually cleared. This code covers both hot surface ignitor failures and situations where gas never reaches the burner.
Common Causes
- Failed hot surface ignitor (HSI) — The ignitor glows to light the gas but cracks or burns out over time. A cracked ignitor may glow dimly or not at all, preventing ignition.
- Dirty or failed flame sensor — Even if the burner lights, a coated flame sensor won’t confirm the flame, causing the board to abort the cycle and log an ignition failure.
- No gas pressure or low gas pressure — A closed shutoff valve, failed gas valve, or low supply pressure prevents gas from reaching the burners.
- Induced draft motor or pressure switch fault — If the draft inducer is not running at speed or a pressure switch is stuck open, the board will not open the gas valve at all, which looks like an ignition failure.
Step-by-Step Fix
- Check gas supply — Confirm the manual shutoff valve is open. Check that other gas appliances in the building are working. If gas supply is confirmed, check furnace gas valve voltage (24VAC on the valve coil terminals during an ignition attempt indicates the board is commanding it open).
- Inspect the hot surface ignitor — With power off, remove the ignitor (typically one screw). Visually inspect for cracks. Test resistance with a multimeter — most HSIs read 40–100 ohms when cold. An open circuit (OL) means it is broken; replace it.
- Clean the flame sensor — Remove the sensor rod and clean with fine steel wool or emery cloth. Reinstall and retry.
- Check the induced draft motor — Power the furnace and listen for the inducer to start at the beginning of the heat cycle. If it runs sluggishly or not at all, test the inducer motor and its capacitor.
- Reset and monitor — After repairs, restore power and initiate a heat call. Watch the ignition sequence: inducer starts → pressure switch closes → ignitor glows → gas valve opens → flame lights. If any step fails, that component is the fault.
Parts Often Needed
| Part | Notes |
|---|---|
| Hot surface ignitor | Most common fix; verify correct model (120V or 80V HSI) |
| Flame sensor rod | Clean first; replace if cleaning does not help |
| Inducer motor capacitor | Test before replacing the full motor |
| Gas valve | Replace if voltage is present at coil but valve does not open |
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 HVAC part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
If gas supply is confirmed but the valve is not opening and you are not familiar with 24VAC control circuits, have a licensed HVAC technician diagnose the gas valve and control board. Do not bypass safety controls to force ignition.