Goodman furnace 3 flashes: Pressure Switch Stuck Open
Try DIY first, then call a pro
What does 3 flashes mean on a Goodman furnace? After the induced-draft blower starts, the pressure switch never closes. The control locks out, then auto-resets and retries. Code: three short flashes and a pause.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
Homeowner checks for Goodman furnace 3 flashes
This is a limited outdoor observation check, not a complete furnace repair. If you smell gas or a carbon monoxide alarm sounds, leave the home right away without operating any switches, then call the gas utility or 911 from outside. Never bypass a safety switch or reset the furnace over and over.
- Turn the furnace off
Turn off the furnace at the thermostat and its nearby power switch before checking the vent ends. Keep the furnace cabinet closed.
- Find the vent ends from ground level
Locate the furnace intake and exhaust pipe ends where they leave the house. Only check ends you can see and reach while standing on the ground. Do not climb a ladder or go onto the roof.
- Clear loose snow or leaves by hand
If it is safe to stand there, brush away loose surface snow or leaves from around the openings by hand, without tools. Do not reach into the pipes, chip at ice, or remove or modify any pipe, cap, or screen.
- Stop and call if anything else is wrong
Leave the furnace off and call a technician if you find ice, a nest, a damaged pipe, or anything you cannot clear safely by hand. After clearing only loose surface snow or leaves, restore power and observe one heating cycle. If the code returns, turn the furnace off and arrange service.
If venting and hoses are clear and it still trips, the switch or inducer is failing. DIY part cost: $25–60 — a pro visit for this class of fault typically runs $150–350.
What causes it (in order of likelihood)
- Disconnected or cracked pressure-switch hose (official) DIY-CHECKABLE
- Blocked flue / intake pipe, blocked drain, or weak inducer DIY-CHECKABLE
- Failed pressure switch or wiring TECH
Parts referenced by this code
Always match parts against your model's parts list — part numbers vary within a series.
Questions about this code
What does 3 flashes mean on a Goodman furnace?
After the induced-draft blower starts, the pressure switch never closes. The control locks out, then auto-resets and retries. Code: three short flashes and a pause.
How do I fix Goodman furnace 3 flashes?
From ground level, you can check the outdoor intake and exhaust ends and clear loose snow or leaves by hand if safe. Hoses, the condensate trap, the inducer, and the switch are for a technician.
How much does it cost to fix Goodman furnace 3 flashes?
If clearing a blocked vent end solves it, there may be no repair bill. Otherwise cost depends on whether the hose, drain, inducer, or switch is at fault.
Related symptoms
These symptoms can appear alongside this code. The link is an association, not a diagnosis, and code meanings vary by brand, model and control.
Applies to
GMS8 · GDS8 · GHS8 · GMSS96 · GMH8 · GDH8
Different Goodman generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Goodman GMS8/GDS8/GHS8 Service Manual (RS6612006), p.42 — “three short flashes followed by a pause”
Verified against Goodman GMSS96 Service Manual, p.32
Last verified 2026-07-06 · page updated 2026-10-07 · how we verify
Related Goodman furnace codes
These codes use the same single red led — flash codes system.
| Pattern | Meaning |
|---|---|
| 2 flashes | Pressure Switch Stuck Closed |
| 4 flashes | Open Primary Limit Switch |
| 1 flash | Ignition Lockout — Flame Not Established After 3 Tries |
| 5 flashes | Flame Sensed With No Call for Heat |