How To Fix the Goodman Furnace Code f02

Recently, a member of our Facebook group, John, reached out about an issue with his Goodman Furnace and it displaying a f02 code. I decided to answer it here for everyone to see how I troubleshoot and fix it.

Q: What does the f02 error code on a Goodman furnace indicate?

A: The f02 error code typically indicates a vacuum issue in the pressure switch of the Goodman furnace. This prevents the furnace from operating correctly as the pressure switch fails to close due to insufficient vacuum.

Q: What are the typical causes of this error?

A: Common causes include:

  1. Pressure Switch Hose Problems: If the hose is blocked, pinched, cracked, or connected improperly, it can prevent vacuum formation. Inspect and repair the hose if necessary.
  2. Blocked Flue or Weak Induced Draft Blower: These can impede the creation of adequate vacuum. Ensure the flue is clear of any blockages and that the draft blower is functioning properly.
  3. Pressure Switch Issues: Incorrect setpoint or malfunctioning contacts can cause errors. Adjust the setpoint or repair contacts as needed.
  4. Wiring Issues: Loose or improper wiring connections can disrupt furnace operation. Check and secure all connections.
  5. Blockages and Water Backup: Blockages in the flue or chimney and water backed up in the heat exchanger or drain can cause issues. Clear any blockages and ensure there’s no water backup.
  6. Vent Motor and Intake Checks: Confirm that the small vent motor is running and there’s no blockage in the vent or intake. If the furnace has a connected drain, ensure no water is backed up in the hoses.

Q: How do you troubleshoot the f02?

A: Here are the steps I follow:

How do you troubleshoot the f02?
  1. Inspect the Flue and Inlet Air Piping: Look for blockages and ensure correct installation.
  2. Check the Pressure Switch Hose: Look for blockages or improper connections.
  3. Verify Inducer and Vent Motor Operation: Ensure they create a sufficient vacuum.
  4. Check Wiring Connections: Make sure they are secure and correctly attached.
  5. Pressure Switch Test: Disconnect the hose from the inducer and suck on it to check for a clicking sound.

Troubleshooting Chart:

IssueCheckpointsSolution
Blocked FlueInspect for blockagesClear blockages
Pressure Switch IssuesInspect hose, adjust setpointReattach/replace hose, adjust switch
Inducer Motor FaultVerify operationReplace if necessary
Wiring ProblemsEnsure connections are tightTighten or redo connections

Advanced Troubleshooting:

  • Pressure Switch Test: Disconnect the rubber hose from the inducer but keep it attached to the switch. Call for heat and suck on the hose. A clicking sound from the switch and ignition of burners indicates proper function.
  • Pressure Switch Bypass Test: Start the inducer and bypass the pressure switch with a jumper wire to check if the furnace ignites.

Technical Equipment: For more accurate diagnostics, use a vacuum manometer or Magnehelic gauge to measure the vacuum between the inducer and the switch. The vacuum should meet or exceed the required amount as marked on the switch label.

Q: What if I don’t have the technical equipment for advanced troubleshooting?

A: As a homeowner, you might not possess these tools. In this case, contacting an onsite technician is advisable. Without precise measurements, you may end up changing parts based on guesswork. Start with replacing the pressure switch as it’s cost-effective, and then consider the inducer assembly if the problem persists.

Q: Any tips on preventing the f02 error?

A: Regular maintenance is key. Ensure the flue and air intake systems are clear, and the pressure switch and motors are in good working condition. Regular checks can prevent issues from developing.


John, I hope this detailed explanation helps you understand and address the f02 error on your Goodman furnace. If you have any more questions, feel free to ask!

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