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Goodman gas furnace 6 red flashes: Overheat / flue or venting fault

Gas furnace, Canada and United States

This code means one of two things, depending on your model. Find your model family below, then read the section for it. The model number is on the rating label on the side of the unit.

Find your model family

If you haveIt means
GDH8, GDS8, GKS9, GMH8 / AMH8, GMH95 / GCH95 / AMH95, GMS8 / AMS8, GMSS92 / GCSS92 / AMSS92, GMSS96 / GCSS96 / AMSS96 / ACSS96, GMES80 / GCES80 / AMES80 / ACES80, GMES92, GMES96 / GCES96 / AMES96 / ACES96 Rollout switch open or control board fuse blown
GMEC96 / GCEC96 / AMEC96 / ACEC96 Pressure switch cycling lockout

Rollout switch open or control board fuse blown

On GDH8, GDS8, GKS9, GMH8 / AMH8, GMH95 / GCH95 / AMH95, GMS8 / AMS8, GMSS92 / GCSS92 / AMSS92, GMSS96 / GCSS96 / AMSS96 / ACSS96, GMES80 / GCES80 / AMES80 / ACES80, GMES92, GMES96 / GCES96 / AMES96 / ACES96.

The rollout switch circuit is open, which can mean flames have rolled out of the burner area, or the 3 A fuse on the control board has blown. The furnace does not run. On GKS9 furnaces this code covers the rollout switch only.

This needs a licensed gas technician. There is nothing safe to check yourself. Leave the covers on and book a professional.

This involves the flue or exhaust. A blocked or leaking flue can let carbon monoxide into the home.

What causes it

GMS8, GMH8, GMSS9, GMH95 and GKS9 boards

  1. Flame rollout from misaligned burners, a blocked flue or air inlet pipe, or a failed inducer. On GMS8 and GMH8 furnaces the technician also checks the heat exchanger.

    Book a licensed gas technician

  2. Loose or wrongly connected wiring.

    Book a licensed gas technician

  3. A short in the 24 V control or safety circuits has blown the 3 A fuse on the control board (not listed for GKS9).

    Book a licensed gas technician

  4. The rollout switch itself is faulty.

    Book a licensed gas technician

GMES80, GMES92 and GMES96 boards

  1. Flame rollout from misaligned burners, a blocked flue or a failed inducer.

    Book a licensed gas technician

  2. Loose or wrongly connected wiring.

    Book a licensed gas technician

  3. A short in the 24 V control or safety circuits has blown the 3 A fuse on the control board.

    Book a licensed gas technician

  4. The rollout switch itself is faulty.

    Book a licensed gas technician

How to read this code on your unit

Booking a licensed gas technician

Book a licensed gas technicianlicensed gas technician

  1. Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
  2. Note the code, how often it appears, and the model and serial numbers from the rating label.
  3. Book a licensed gas technician and give them those details.

Models that show this code

220 models in 11 ranges
RangeModels
GDH8GDH80403AN, GDH80403AX, GDH80603AN, GDH80603AX, GDH80804BN, GDH80804BX, GDH81005CN, GDH81005CX
GDS8GDS80403AN, GDS80403AX, GDS80603AN, GDS80603AX, GDS80804BN, GDS80804BX, GDS81005CN, GDS81005CX
GKS9GKS90453BX, GKS90703BX, GKS90704CX, GKS90904CX, GKS90905DX, GKS91155DX
GMH8 / AMH8GMH80403AN, GMH80403AX, GMH80603AN, GMH80603AX, GMH80604BN, GMH80604BX, GMH80803BN, GMH80803BX, GMH80804BN, GMH80804BX, GMH80805CN, GMH80805CX, GMH81005CN, GMH81005CX, GMH81205DN, GMH81205DX, GMH81405DN, AMH80403AN, AMH80403AX, AMH80603AN, AMH80603AX, AMH80604BN, AMH80604BX, AMH80803BN, AMH80803BX, AMH80804BN, AMH80804BX, AMH80805CN, AMH80805CX, AMH81005CN, AMH81005CX, AMH81205DN, AMH81205DX, AMH81405DX
GMH95 / GCH95 / AMH95GMH950453BX, GMH950703BX, GMH950704CX, GMH950904CX, GMH950905CX, GMH950905DX, GMH951155DX, AMH950453BX, AMH950703BX, AMH950704CX, AMH950904CX, AMH950905CX, AMH950905DX, AMH951155DX, GCH950453BX, GCH950703BX, GCH950704CX, GCH950905DX
GMS8 / AMS8GMS80403AN, GMS80403AX, GMS80603AN, GMS80603AX, GMS80604BN, GMS80604BX, GMS80804BN, GMS80804BX, GMS80805CN, GMS80805CX, GMS81005CN, GMS81005CX, GMS81205DN, GMS81205DX, GMS81405DN, AMS80403AX, AMS80603AX, AMS80604BX, AMS80804BX, AMS80805CX, AMS81005CX, AMS81205DX, AMS81405DN
GMSS92 / GCSS92 / AMSS92GMSS920402BN, GMSS920403AN, GMSS920603BN, GMSS920803BN, GMSS920804CN, GMSS920805CN, GMSS921004CN, GMSS921005CN, GMSS921205DN, AMSS920402BN, AMSS920403AN, AMSS920603BN, AMSS920803BN, AMSS920804CN, AMSS920805CN, AMSS921004CN, AMSS921005CN, AMSS921205DN, GCSS920402BN, GCSS920603BN, GCSS920804CN, GCSS921005CN
GMSS96 / GCSS96 / AMSS96 / ACSS96GMSS960402BN, GMSS960403AN, GMSS960603BN, GMSS960803BN, GMSS960804CN, GMSS960805CN, GMSS961005CN, GMSS961205DN, AMSS960402BN, AMSS960403AN, AMSS960603BN, AMSS960803BN, AMSS960804CN, AMSS960805CN, AMSS961005CN, AMSS961205DN, GCSS960402BN, GCSS960603BN, GCSS960804CN, GCSS961005CN, GCSS961205DN, ACSS960402BN, ACSS960603BN, ACSS960804CN, ACSS961005CN, ACSS961205DN
GMES80 / GCES80 / AMES80 / ACES80GMES800403AN, GMES800403AX, GMES800603AN, GMES800603AX, GMES800603BN, GMES800603BX, GMES800604BN, GMES800604BX, GMES800803BN, GMES800803BX, GMES800804BN, GMES800804BX, GMES800804CN, GMES800804CX, GMES800805CN, GMES800805CX, GMES801005CN, GMES801005CX, GMES801205DN, AMES800403AX, AMES800603AX, AMES800603BN, AMES800604BX, AMES800803BX, AMES800804BX, AMES800804CX, AMES800805CX, AMES801005CX, AMES801205DX, GCES800403AN, GCES800403AX, GCES800603AN, GCES800603AX, GCES800804BN, GCES800804BX, GCES801005CN, GCES801005CX, ACES800403AN, ACES800403AX, ACES800603AN, ACES800603AX, ACES800804BX, ACES801005CX
GMES92GMES920403AN, GMES920603BN, GMES920803BN, GMES920804CN, GMES920805CN, GMES921004CN, GMES921005CN, GMES921205DN
GMES96 / GCES96 / AMES96 / ACES96GMES960403AN, GMES960603BN, GMES960803BN, GMES960804CN, GMES960805CN, GMES961005CN, GMES961205DN, AMES960403AN, AMES960603BN, AMES960803BN, AMES960804CN, AMES960805CN, AMES961005CN, AMES961205DN, GCES960403BN, GCES960603BN, GCES960804CN, GCES961005CN, GCES961205DN, ACES960403BN, ACES960603BN, ACES960804CN, ACES961005CN, ACES961205DN

Where this comes from

Checked against the manufacturer's manual on 9 October 2026.

Pressure switch cycling lockout

On GMEC96 / GCEC96 / AMEC96 / ACEC96.

The pressure switch opened five times during one heating cycle, so the furnace has locked out.

This needs a licensed gas technician. There are a few safe checks you can do first, marked below. Anything inside the unit is a job for a professional.

This involves the flue or exhaust. A blocked or leaking flue can let carbon monoxide into the home.

What causes it

  1. Too much restriction in the venting, for example a blocked intake or vent termination outside.

    Check the outside flue or vent terminal is clearYou can do this

    1. Find where the flue or vent pipe ends outside the building. High-efficiency furnaces and some water heaters also have a combustion air intake pipe beside it: check that one too. On some outdoor water heaters the flue outlet is part of the front cover.
    2. Look for anything blocking it, such as leaves, a bird or insect nest, snow, plants, or items stored against the wall.
    3. Cut back plants and move stored items away from it. Do not touch, poke into or hose the flue outlet. If something is inside it, book a service.
      The terminal can be hot. Do not climb onto the roof or use a ladder to reach it; if it is out of reach, book a technician.

    Reset a Goodman furnace lockout onceYou can do this

    1. Look through the sight glass on the blower compartment, note the colour of the status light and count the flashes. Write them down first, because cutting the power clears the code.
    2. Turn off the electrical power to the furnace, leave it off for more than 20 seconds, then turn it back on. Or turn the thermostat down until it stops calling for heat, wait a few seconds (no more than 20), then set it back.
    3. Left alone, the control also tries again by itself after one hour.
    4. Reset it once only. If the furnace locks out again, or locks out often, leave it off and book a qualified technician.
      A repeat lockout means the fault is still there. Do not keep resetting it.

    Book a licensed gas technician

  2. The pressure switch tubing is leaking.

    Book a licensed gas technician

How to read this code on your unit

Booking a licensed gas technician

Book a licensed gas technicianlicensed gas technician

  1. Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
  2. Note the code, how often it appears, and the model and serial numbers from the rating label.
  3. Book a licensed gas technician and give them those details.

Models that show this code

30 models in 1 range
RangeModels
GMEC96 / GCEC96 / AMEC96 / ACEC96GMEC960302BN, GMEC960303AN, GMEC960402BN, GMEC960403AN, GMEC960603AN, GMEC960603BN, GMEC960803BN, GMEC960804CN, GMEC961004CN, GMEC961005CN, GMEC961205DN, AMEC960302BN, AMEC960303AN, AMEC960402BN, AMEC960403AN, AMEC960603AN, AMEC960603BN, AMEC960803BN, AMEC960804CN, AMEC961004CN, AMEC961005CN, AMEC961205DN, GCEC960403BN, GCEC960603BN, GCEC960803BN, GCEC961005CN, ACEC960403BN, ACEC960603BN, ACEC960803BN, ACEC961005CN

Where this comes from

Checked against the manufacturer's manual on 9 October 2026.

Other Goodman gas furnace codes

Code Meaning What you can do
EE2 Pressure switch not closing Call a pro
EE3 Primary limit switch open Safe checks first, then a pro
EE8 High-stage pressure switch closed at start of heating Call a pro
EE9 High-stage pressure switch not closing Call a pro
EEd Auxiliary limit switch open (blower compartment) Safe checks first, then a pro
2 red flashes Pressure switch closed when it should be open Call a pro
3 red flashes Pressure switch not closing Safe checks first, then a pro
3 double red flashes High-stage pressure switch stuck open Call a pro
4 red flashes Overheat (depends on model) Safe checks first, then a pro
5 red flashes Sensor fault or overheat (depends on model) Safe checks first, then a pro
11 red flashes Ignition failure or overheat (depends on model) Call a pro
12 red flashes Flue or venting fault / ignition failure (depends on model) Call a pro

See all overheat codes on gas furnaces across brands.

See all flue or venting fault codes on gas furnaces across brands.

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