Goodman GMSS920803BN Error Code 2 Flashes: Pressure Switch Stuck Closed
What Does Code 2 Flashes Mean?
Two flashes on the Goodman GMSS920803BN diagnostic LED indicate that the pressure switch circuit is closed when the Integrated Control Module expects it to be open. Before it starts a heat cycle, the board verifies the pressure switch is sitting in its resting open state. That check proves the switch is capable of responding to draft. If the board already sees a closed circuit while the inducer is off, it refuses to start the sequence.
On this single-stage furnace the pressure switch is a safety interlock: it is supposed to close only after the induced-draft blower pulls the correct vacuum, confirming exhaust gases are moving safely. A switch that is closed at rest defeats that proof, so the board blocks ignition entirely. The manufacturer attributes this to the induced-draft pressure switch contacts sticking closed, or to a short in the pressure switch circuit wiring that makes an open switch look closed to the board.
This is the mirror image of the neighboring 3-flash condition on the same board. Three flashes means the inducer runs but the switch fails to close, whereas two flashes means the switch is already closed before the inducer even starts. Reading the flash count correctly matters, because the two point to opposite faults in the same circuit.
What You'll Notice
- The furnace will not begin a heat cycle and the LED repeats a two-flash pattern
- The induced-draft (inducer) blower does not start, unlike the 3-flash condition where it runs
- No ignition attempt occurs at all — no igniter glow, no burner flame
- The fault appears immediately on a call for heat rather than partway through startup
- The problem may be intermittent if the switch contacts stick only some of the time
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Pressure switch contacts sticking closed | Most common | ✗ Call a pro → |
| Short in pressure switch circuit wiring | Common | ✗ Call a pro → |
How This Is Diagnosed
A technician confirms the pressure switch is electrically closed while the inducer is off, which is the defining condition for this code. With power removed, the switch contacts are tested for continuity in the resting state — a healthy switch reads open until draft is applied, so continuity at rest indicates stuck contacts.
If the switch itself proves good, the wiring and connector in the pressure switch circuit are inspected for a short that would bridge the circuit and imitate a closed switch. The fix is to replace a switch with sticking contacts or repair the shorted wiring; both are service tasks rather than homeowner work.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The LED shows two flashes and the inducer never starts
- The furnace fails to begin any heat cycle even after power is cycled at the breaker
- A pressure switch was recently replaced and the two-flash code returned
- You can see damaged, pinched, or melted wiring near the pressure switch
Frequently Asked Questions
What is the difference between 2 flashes and 3 flashes on my Goodman GMSS920803BN?
Two flashes means the pressure switch is already closed before the inducer starts (stuck closed or a wiring short), so the furnace never begins. Three flashes means the inducer is running but the switch fails to close, usually from a blocked vent, clogged drain, or kinked hose. They are opposite faults in the same circuit.
Can I fix a stuck-closed pressure switch myself?
No. Diagnosing whether the contacts are stuck or the wiring is shorted requires electrical testing, and the repair is a switch replacement or wiring correction. This is a job for a qualified technician.
Sources
✓ Verified against manufacturer service manual — March 2026