HVAC Code Lookup

Goodman Furnace Code 3

Soft lockoutShown as: 3 flashes, then a pause, repeating

Pressure switch open. The draft inducer is running but the vent pressure switch never closed, so the furnace will not light. Usually a venting or drain blockage.

Manual wording: “Pressure Switch stuck Open”

Documented for: Goodman GMS8, GMH8, GDS8, GDH8, GHS8, GME8, GMES80, GCES80, GMSS92, GMSS96, GCSS96 (single red diagnostic LED)

Likely causes, most common first

  1. Pressure switch hose blocked, pinched or connected improperly
  2. Blocked flue or weak induced draft blower
  3. Blocked inlet air pipe or blocked drain system (condensing models)
  4. Incorrect pressure switch setpoint or malfunctioning switch contacts
  5. Loose or improperly connected wiring

What you can safely check yourself

  • Go outside and check the intake and exhaust pipes for snow, ice, leaves, a bird nest or other blockage
  • On a high-efficiency furnace, check the condensate drain line and trap for a clog or standing water
  • Check that the vent terminal is not buried by drifting snow

When to call a technician

If the pipes and drain are clear, the pressure switch, hose and induced draft blower need a technician. Do not jumper or bypass the pressure switch.

A Goodman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Goodman codes