Payne PG95ESA Error Code 31: HPS Pressure Switch Did Not Close or Reopened
What Does Code 31 Mean?
Status code 31 (three short flashes followed by one long flash) means the inducer housing pressure switch — the HPS — did not close when the inducer started, or closed and then reopened. This switch is the control's proof that the inducer motor is pulling proper draft before and during combustion. Without that proof the furnace will not light, and if the HPS stays open for an extended time the control locks out for 3 hours before retrying.
Because the PG95ESA is a condensing furnace, its venting and condensate system are tightly linked to this switch. The manual's causes for code 31 include a blocked or restricted vent pipe, restricted condensate drainage or a plugged collector box, a defective inducer motor that can't build draft, excessive wind at the vent terminal, inadequate combustion air supply, low inlet gas pressure (where a low gas pressure switch is used), and cracked or disconnected pressure switch tubing. Many of these are venting or drainage problems specific to a high-efficiency, condensing design.
This is a "did not close" fault. It is the opposite of code 23 (a pressure switch that did not open), and it is closely related to code 32, which is the same failure on the collector box low pressure switch (LPS). Diagnosing draft, venting, condensate, and the inducer is professional work.
What You'll Notice
- The amber LED flashes three short flashes followed by one long flash (code 31)
- The inducer runs but the furnace never lights, because draft is not being proven
- The furnace may try, drop out, and retry, then lock out for about 3 hours if the switch stays open
- You may notice a blocked or dripping vent, standing water near the furnace, or a clogged condensate drain
- The problem can worsen in high wind or very cold weather affecting the vent terminal
Common Causes
How This Is Diagnosed
A technician works down the draft path. They confirm the inducer runs and check the vent and intake pipes for blockages, sagging, or obstruction, then check the condensate drain and collector box for restriction, since backed-up condensate can keep the HPS open. Pressure switch tubing is inspected for cracks, kinks, or disconnection.
If venting and drainage are clear, they measure the inducer's draft and evaluate whether the motor is producing enough pressure to close the switch, and verify the switch itself responds correctly. These checks span the vent system, condensate drainage, inducer motor, and pressure switch — professional diagnosis rather than a homeowner task. Clearing an obviously blocked outdoor vent terminal is the most a homeowner should attempt, and only if it can be reached safely.
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 inducer runs but the furnace won't light and shows code 31
- The furnace locks out for about 3 hours and then repeats the failure
- There are signs of a blocked vent, restricted condensate drain, or standing water at the furnace
- Diagnosis would require measuring draft or testing the inducer motor and pressure switch
Frequently Asked Questions
What does code 31 mean on a Payne PG95ESA?
The inducer housing pressure switch (HPS) did not close or reopened, so the control can't confirm the inducer is establishing safe draft. Common causes are a blocked vent or condensate drain and a weak inducer motor.
Why does a clogged condensate drain cause code 31?
On this condensing furnace, backed-up condensate in the collector box or drain can raise pressure and keep the pressure switch from closing. Clearing the restriction is part of the diagnosis, which a technician should perform.
✓ Verified against manufacturer service manual — March 2026