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ErrBase

Goodman Furnace 9H Error Code: High Pressure Switch Open

Quick Answer

Goodman 9H indicates the high pressure switch opened - either not closing during startup or opening unexpectedly during a heat cycle. On two-stage condensing furnaces (GMVC96), this often points to a restriction in the secondary heat exchanger caused by condensate backing up. A blocked condensate drain is the most common root cause and the first thing to rule out.

Goodman 9H indicates the high pressure switch opened - either not closing during startup or opening unexpectedly during a heat cycle. On two-stage condensing furnaces (GMVC96), this often points to a restriction in the secondary heat exchanger caused by condensate backing up. A blocked condensate drain is the most common root cause and the first thing to rule out. Vent pipe restrictions cause the next largest share. If drain and vent are clear, the pressure switch itself may have drifted out of spec or failed. Pressure switch testing requires either a manometer or a hand-operated vacuum pump with a gauge to verify trip point.

GoodmanFurnaceSeverity: highDifficulty: intermediate74% DIY Success
Time to Fix
30–90 min
Difficulty
intermediate
Parts Cost
$20 – $45
Tools Needed
Wet/dry vacuum, Multimeter

What Does the 9H Code Mean?

9H means the high-stage pressure switch did not close or opened mid-cycle. On 96% AFUE models, a backed-up condensate drain is the most common trigger. Check the drain first, then the vent pipe.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Clogged secondary heat exchanger from condensate backup40%
Condensate drain line blocked or frozen24%
Pressure switch failed or out of calibration22%
Vent pipe restriction or bird/debris blockage14%

Symptoms You May Notice

  • Furnace not completing a heat cycle
  • LED flashing 9H on control board
  • Furnace starts and shuts down after a few minutes
  • Water visible around furnace base (condensate overflow)

Can you reset a Goodman furnace to clear the 9H code?

After clearing the condensate drain or vent obstruction, flip the furnace circuit breaker off for 30 seconds, then restore power and call for heat. If 9H returns within one heat cycle, the secondary heat exchanger likely needs professional cleaning.

Tools Required for Diagnosis

Wet/dry vacuumMultimeterFlashlightVacuum pump with gauge (for switch testing)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

1

Check the condensate drain line from the furnace to the drain point

Check the condensate drain line from the furnace to the drain point. Look for standing water at the trap, a frozen section in an unheated space, or a blocked outlet. Flush with warm water or use a wet/dry vac at the drain outlet.

2

Visually inspect the vent pipe termination outside the building

3

Locate the high-stage pressure switch

4

If drain and vent are clear and switch tests good

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name
High-Stage Pressure SwitchB1370732 · $20–$45

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs
Labor Approach
Our Verdict
REPAIR
Estimated Cost: $33 (Parts) vs $2350 (New Machine)

Frequently Asked Questions

What is the secondary heat exchanger on a Goodman 96% furnace?
On high-efficiency condensing furnaces, the secondary heat exchanger extracts additional heat from the flue gases, causing them to condense into water. When the condensate drain is blocked, this water backs up and restricts the secondary coil, reducing inducer pressure and triggering the high pressure switch.
How is 9H different from F02?
F02 fires when the pressure switch is stuck closed before the inducer starts. 9H fires when the high-stage pressure switch opens during operation, meaning the inducer started but cannot maintain the required pressure. Both can be caused by condensate drain issues, but 9H is more likely to involve the secondary heat exchanger.
Can I clean the secondary heat exchanger myself?
Basic flushing of the condensate drain and trap is a DIY task. Deep cleaning of the secondary coil itself typically requires professional equipment and is best handled by a licensed HVAC technician, especially if scale or biological growth has built up.

Related Goodman Furnace Error Codes

Code: HUBGoodman Furnace Error Codes: LED Flash Code Guide for GMVC and GMSS SeriesCode: F02Goodman Furnace F02 Error Code: Pressure Switch Stuck ClosedCode: E5Goodman Furnace E5 Error Code: Pressure Switch ErrorCode: RESETHow to Reset a Goodman Furnace and Clear Error Codes

Models Known to Experience 9H Errors

This repair applies to most Goodman furnaces with this error code. Common model numbers include:

GMVC96, GMSS92, GCVC96, AMVC96, ASST96

Last verified for technical accuracy on March 14, 2026