Goodman gas_furnace Error Code 3 flashes

What does 3 flashes mean?

Pressure switch is closed when it should be open during initial startup check.

Common causes

• Failed pressure switch stuck closed
• Pressure switch hose connected backwards
• Short circuit in pressure switch wiring

Diagnostic & testing steps

1. 1. Unplug pressure switch hose and verify switch opens
2. 2. Check hose connection orientation (port/polarity)
3. 3. Test switch with multimeter - should be normally open
4. 4. Replace pressure switch if stuck closed

Tools required

• Multimeter

OEM parts & part numbers

Pressure Switch

Part numbers: B1370163, B1370135

Safety warning

⚠️ A stuck-closed pressure switch can allow operation with a blocked flue. Replace immediately.