Goodman Furnace 2 Flashes — What It Means
When your Goodman furnace flashes its diagnostic LED twice in a repeating pattern, the control board has detected a pressure switch error with the switch stuck closed. The board is seeing the pressure switch circuit closed when it expects it to be open, or it has detected a short in the pressure-switch circuit. The pressure switch is a safety device that proves the inducer blower is creating proper draft before allowing gas to flow. A stuck-closed switch tells the board that something is wrong with the switch itself, the wiring, or the draft conditions in the furnace.
This fault can stem from a genuinely failed pressure switch that will not open electrically, a short or miswiring in the harness, pinched or cracked pressure-sensing tubing, or an inducer and venting problem that prevents normal pressure cycling. The most common real-world fix is replacing the pressure switch after confirming the tubing and wiring are intact, but you must test rather than assume.
Common Causes
- Failed or mechanically stuck pressure switch The switch contacts remain closed even when draft pressure is wrong, often due to internal contact failure or mechanical jamming inside the switch body.
- Shorted or miswired pressure-switch circuit Damaged wiring, pinched harness insulation, corroded terminals, or incorrect connections create a continuous closed circuit the board reads as a stuck switch.
- Cracked, pinched, or blocked pressure-switch tubing The rubber or silicone hose that senses draft pressure has a crack, kink, or blockage that prevents the switch from sensing true furnace pressure and cycling correctly.
- Inducer blower or venting problem A failing inducer motor, blocked flue pipe, or restricted combustion-air intake can create abnormal draft that holds the pressure switch in the wrong state during startup.
- Loose or corroded electrical connectors Poor contact at the pressure-switch spade terminals or control-board connector can mimic a closed or shorted circuit and trigger the fault code.
Step-by-Step Fix
- Verify the flash code by watching the diagnostic LED on your furnace control board and counting the number of flashes, then confirm 2 flashes against your model’s fault legend in the installation manual or door label.
- Inspect the pressure-switch tubing for cracks, kinks, disconnections, or blockages by tracing the small rubber hose from the pressure switch to the inducer housing or collector box, and replace any damaged tubing.
- Check all electrical connections at the pressure switch terminals and the control board connector for looseness, corrosion, pinched wires, or visible shorts, and clean or repair any faults you find.
- Test inducer operation by powering the furnace and listening for the draft blower to spin up normally, then inspect the flue pipe and combustion-air intake for obstructions, nests, or ice that would block airflow.
- Measure draft pressure at the pressure-switch port using a manometer or magnehelic gauge while the inducer is running, and compare the reading to the pressure rating stamped on the switch body (for example, 0.72 in. w.c. on some Goodman models).
- Test the pressure switch electrically by disconnecting power, removing the switch wiring, and checking continuity across the terminals with a multimeter while the inducer runs, replacing the switch if it stays closed when draft is absent or fails to operate at its rated pressure.
- Run a full heat cycle after repair to confirm the 2-flash code does not return and the furnace completes its inducer, ignition, and burner sequence without faults.
Parts Often Needed
| Part | Notes |
|---|---|
| Goodman pressure switch | Amazon | Model-specific. Verify the pressure rating stamped on your original switch (in inches water column) and cross-reference your furnace model number before ordering. |
| Pressure switch tubing (rubber or silicone hose) | Amazon | Flexible draft-sensing hose, typically 1/4 inch or 5/16 inch inside diameter. Match the original length and fitting type. |
| Inducer draft blower motor assembly | Amazon | Required if the inducer will not spin or creates insufficient draft. Confirm your furnace model and voltage before purchase. |
When to Call a Pro
Call a licensed HVAC technician if you are uncomfortable working with gas appliances, cannot safely access the pressure switch and tubing, or do not own a manometer to measure draft pressure. A technician should also diagnose the fault if you have replaced the pressure switch and tubing but the 2-flash code returns, because the root cause may be a control-board fault, complex venting issue, or gas-valve problem that requires specialized tools and training. Any work involving gas connections, flue venting, or control-board replacement is best left to a qualified professional to protect your safety and warranty.