If your Goodman furnace cranks through its startup cycle but never actually lights, you’re dealing with one of three likely culprits: the hot surface igniter, the flame sensor, or the control board. (The gas valve is less common than people assume.) A tech can narrow it down with a meter in real time, but observation alone gets you pretty far.
How the Goodman Ignition Sequence Works
Understanding the sequence makes diagnosis easier. When the thermostat calls for heat, the control board runs the inducer motor first to clear the heat exchanger of residual gases. After proving airflow through the pressure switch, the board energizes the hot surface igniter (HSI), waits for it to reach ignition temperature (warm-up times vary by igniter model, but 17 to 34 seconds is a common range), then opens the gas valve and watches for flame through the flame sensor. If no flame is detected within a few seconds, the board closes the gas valve, waits, and tries again. Most Goodman boards allow two or three retry attempts before locking out.
So when you say “it tries to light but never fires,” the question is: at which step does it fail?
Most Likely Cause: The Hot Surface Igniter
This is the first thing I check. The HSI is a fragile silicon carbide or silicon nitride element that glows orange-hot to ignite the gas. They crack. They fail open. They’re consumable parts, and they’re the most common reason a Goodman furnace won’t ignite.
One thing you can check yourself: with the furnace off and power disconnected, look at the igniter. A crack or a broken tip is obvious. Even without visible damage the element can fail electrically, so a clean visual doesn’t clear it. A technician can confirm with a meter in a couple of minutes, and if it’s dead, replacement is straightforward.
If you watch the startup cycle and the igniter never glows at all, that points toward the control board failing to energize it, not the igniter itself.
Second Most Likely: The Flame Sensor
This one gets misdiagnosed constantly. The flame sensor is a small metal rod that sits in the burner flame and proves to the board that combustion is actually happening. When it gets coated with oxidation, it can’t conduct the tiny microamp signal back to the board, and the board shuts off the gas even though the furnace actually lit for a split second.
If you watch closely during a startup attempt and you see the burners light briefly (a small flicker or a pulse of flame) and then go out within a couple of seconds, a dirty flame sensor is the most likely explanation. This is probably the single most common “won’t stay lit” call I get on any gas furnace, not just Goodman.
A tech can clean or replace the sensor quickly, and it’s an inexpensive fix. It’s worth ruling out before anything else when the furnace lights and then immediately cuts off.
Control Board Issues
If the inducer runs, the pressure switch proves, but the igniter never receives voltage, the control board may not be sending the signal. Control board failures can also show up as erratic retry behavior, lockout with no clear cause, or error codes on boards that have LED indicators.
Check your furnace’s door panel. Many Goodman models have a blinking LED and a fault-code chart printed on a sticker inside the door. The blink pattern narrows down the cause considerably before you start swapping parts.
Board diagnosis requires a meter and knowing what voltages to expect at which terminals during each stage. Getting it wrong means replacing an expensive part unnecessarily. Goodman control boards vary widely in price depending on the model; budget for parts plus labor and get a quote before committing.
Gas Valve
The gas valve is less commonly the root cause than people expect, but it does fail. If the igniter glows, the flame sensor is clean, the board is sending the right signals, and there’s still no gas flow, the valve may not be opening. You can sometimes hear a faint click when a valve opens. No click when the board signals it can mean a failed valve or, just as often, a wiring issue upstream.
One thing to confirm before suspecting the valve: make sure the gas supply is actually on. A manual shutoff valve at the furnace that got turned off during maintenance and not turned back on is a real thing that happens.
Do not attempt to bypass or jumper a gas valve to test it. That’s a job for a licensed tech with the right equipment.
What You Can Check Before Calling
A few things are worth confirming before you pick up the phone:
- Look at the igniter (furnace off, power disconnected) for visible cracks or a broken tip.
- Confirm the manual gas shutoff at the furnace is fully open. It gets bumped during filter changes more often than you’d think.
- Pull the air filter. A severely clogged filter can cause pressure switch problems that look like ignition failure.
- Check the fault-code sticker inside the furnace door if the LED is blinking.
Everything past that (meter work on the igniter, cleaning the flame sensor, board diagnosis, anything touching the gas valve or wiring) is a tech job. These aren’t hard calls, but doing them wrong wastes money on parts you didn’t need and, in the gas valve’s case, creates a real safety risk.
When to Call
If you’ve done the quick checks above and the furnace still won’t light, stop cycling it. Repeated failed attempts let raw gas build up in the burner area, which is a safety concern. Two or three tries is enough.
A technician runs through the ignition sequence with a meter in real time, pulls fault codes if the board logged them, and pinpoints the failed component without guessing at parts. Most of these repairs come down to one component plus labor.
If you’re in the Tri-Valley or East Bay, we handle furnace diagnosis and repair. We’ll get you on the schedule quickly, often same or next day when we can. Book at adriumservice.com or call us directly.