Goodman Furnace Fault Codes: What the Blinking Light Is Telling You

A Goodman furnace tells you what’s wrong with a single LED on the control board. It flashes a pattern, pauses, and repeats. You count the flashes between the pauses to get the code, then match it to the legend printed on the sticker inside the access panel. That label is the real authority, because the meaning of a given flash count can differ from one Goodman control board to the next.

Here’s how to read it, what the common codes point to, and where the line is between a safe homeowner check and a job for a tech.

How the Blinking Light Works

There’s a small viewing window on the furnace door, or you’ll see the LED once the front access panel is off. Watch it for a full cycle.

The light flashes a number of times, pauses, then starts over. On some Goodman boards the code is a single number, so four flashes means code 4. On others it’s a two-digit code, so it flashes three times, pauses briefly, flashes once more, and that reads as 31. Count each group separately. Watch it through at least two full cycles to be sure you’ve got the count right.

A couple of states aren’t faults at all:

• Steady LED, no flashing: usually normal. It generally means the control board has power and the furnace is sitting in standby.
• No light at all: usually means no power reaching the board. Check the breaker and the furnace’s own power switch first.

Common Goodman Flash Codes

These are the codes that show up most often on Goodman furnaces. Treat them as a starting point and confirm against the legend inside your panel, because your specific board is the final word.

• 1 flash: ignition or flame failure. The furnace tried to light and couldn’t, or lost the flame and locked out.
• 2 flashes: pressure switch stuck closed.
• 3 flashes: pressure switch open.
• 4 flashes: open high limit switch. This one is often an airflow problem, and a dirty filter or blocked vents is a frequent cause.
• 5 flashes: flame sensed when the gas valve should be off.

Goodman boards also have a rollout switch code, which is a safety device that trips when heat shows up where it shouldn’t. The exact flash count for that and other higher codes varies by model, which is exactly why the label inside your furnace matters more than any list online.

What You Can Safely Check Yourself

Before you call anyone, run through the handful of things that are genuinely safe and that fix a real share of no-heat calls.

Check the filter. A clogged filter chokes airflow and can trip the high limit, which is the 4-flash code on many units. If it’s dirty, swap it and see if the furnace runs.

Check the breaker and the furnace switch. A tripped breaker or a switch that got bumped off, sometimes mistaken for a light switch near the furnace, kills power to the board. That’s your no-light situation.

Check the thermostat. Make sure it’s set to heat, the temperature is set above the room temperature, and the batteries aren’t dead if it uses them.

Check your vents. Make sure supply registers and return grilles aren’t blocked by furniture or rugs. Restricted airflow causes some of the same faults a dirty filter does.

That’s the safe list. If a fresh filter, a reset breaker, and a correct thermostat setting don’t bring it back, the code is pointing at something deeper.

Why the Rest Is a Pro Job

The codes you can’t safely chase are the ones tied to gas and combustion. A pressure switch fault can mean a blocked flue, a bad inducer motor, or a cracked hose, and diagnosing it means testing draft and verifying the venting is clear. An ignition or flame-sensing fault involves the gas valve, the igniter, and the flame sensor working together in a timed sequence. A rollout code is a safety trip that can point to a cracked heat exchanger, which is a carbon monoxide concern and not something to reset and ignore.

These aren’t jobs you fix with a screwdriver and a video. They involve gas, combustion, and safety devices that exist to keep your house from filling with carbon monoxide. A tech tests each part of the sequence, finds the actual cause, and confirms the furnace is safe before it goes back into service. Resetting a furnace that keeps locking out without finding why is how a small problem turns into a dangerous one.

When to Call Us

If your Goodman furnace is flashing a code and a new filter and a breaker check didn’t fix it, give us a call. We’ll read the code, run the diagnostic sequence, and tell you exactly what’s failing and what it takes to fix it. If it’s a safety code, we treat it like one.

We serve Danville, San Ramon, Alamo, and the surrounding Bay Area, usually same or next-day when we can. Call (925) 999-4095 or book at bayareahvacservice.com. I stand behind the work, and on anything involving gas and combustion, I’d rather you call than guess.

Key takeaways

• Goodman furnaces flash fault codes with a single LED on the control board. Count the flashes between pauses to get the code.
• The code legend is on a sticker inside the furnace access panel. That label is the authority for your exact model, since codes can vary between boards.
• A steady LED usually means power is present and the furnace is in standby. No light usually means no power, so check the breaker and the furnace switch.
• The only safe homeowner checks are the filter, breaker, thermostat, and vents. Anything involving the gas valve, pressure switch, flame sensor, or rollout switch is a pro job.

Related questions

Written by Andrew Kuznetsov. Andrew is the founder and owner of Bay Area HVAC Service (ADRIUM Service Solutions). He holds a California Contractor License (CSLB #1136642), EPA 608 certification, and completed factory training at the Daikin/Goodman plant in Houston in 2025. He writes from direct field experience, not marketing copy.

Further reading

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