HVAC Code Lookup

American Standard fault codes

28 documented codes for American Standard furnaces, each cited to the manufacturer's own manual. Find your code in the table, then jump to what it means, the likely causes, what you can safely check, and when to call a technician.

American Standard Heating and Air Conditioning is a Trane Technologies brand and shares furnace platforms and integrated furnace control (IFC) boards with Trane. Older Silver/Gold 80 and 95 furnaces (*UD1/*DD1, CUB1/CDB1) use a single red diagnostic LED that blinks a count; current models (A801X, A951X, S8V2, S9V2 and the Silver/Gold/Platinum 80 and 95 lines) use a seven-segment display showing E-codes. Wording differs slightly from the Trane version of the same table - for example American Standard prints '4 Flashes --- Open Temperature Limit Circuit' where Trane prints 'Open High Limit Device'.

Looking it up by flash count?

If you counted LED flashes rather than reading a code number, these are the codes that start with that many flashes:

  • 2 flashes: 2 Flashes (System lockout)
  • 3 flashes: 3 Flashes (Draft pressure error)
  • 4 flashes: 4 Flashes (Open temperature limit circuit)
  • 5 flashes: 5 Flashes (Flame is being detected when there should be no flame present)
  • 6 flashes: 6 Flashes (The 115 volt AC line and neutral are reversed at the furnace, the furnace is poorly grounded, or supply voltage is too low)
  • 7 flashes: 7 Flashes (Gas valve circuit error)
  • 8 flashes: 8 Flashes (Low flame sense signal)
  • 9 flashes: 9 Flashes (The control is directing the technician to check the igniter circuit and the voltage between line neutral and 24VAC common, which points at an igniter or grounding problem)

Furnace codes

CodeMeaningSeverity
Flashing SlowRed LED flashing slowly and steadilyNormal standbyStatus
Flashing FastRed LED flashing rapidly and steadilyNormal operation with an active call for heatStatus
Continuous ONLED on solid, never blinkingThe integrated furnace controlHard lockout
Continuous OFFLED completely darkThe control board is not receiving powerWarning
2 Flashes2 flashes, pause, repeatSystem lockoutHard lockout
3 Flashes3 flashes, pause, repeatDraft pressure errorSoft lockout
4 Flashes4 flashes, pause, repeatOpen temperature limit circuitSoft lockout
5 Flashes5 flashes, pause, repeatFlame is being detected when there should be no flame presentSafety fault
6 Flashes6 flashes, pause, repeatThe 115 volt AC line and neutral are reversed at the furnace, the furnace is poorly grounded, or supply voltage is too lowWarning
7 Flashes7 flashes, pause, repeatGas valve circuit errorSafety fault
8 Flashes8 flashes, pause, repeatLow flame sense signalWarning
9 Flashes9 flashes, pause, repeatThe control is directing the technician to check the igniter circuit and the voltage between line neutral and 24VAC common, which points at an igniter or grounding problemWarning
E01Internal integrated furnace control failureHard lockout
E2.1Retry exceededHard lockout
E2.2Recycles exceededHard lockout
E2.3The control commanded the gas valve on and the valve did not energize, ten times in a rowHard lockout
E3.1The pressure switch is reading closed when the control expects it to be open, which the control calls a shorted pressure switchSoft lockout
E3.2The pressure switch will not close, so the control cannot prove the draft inducer is moving flue gas and will not open the gas valveSoft lockout
E04A safety limit has opened: the main thermal limit, a flame rollout switch, or the reverse airflow switchSafety fault
E05The control is sensing a flame when there should not be one - for example with the gas valve commanded offSafety fault
E6.1Line and neutral are reversed in the 115 volt supply to the furnaceWarning
E6.2The furnace does not have a good electrical ground, which the control needs in order to sense flame reliablyWarning
E6.3Igniter faultHard lockout
E7.1The gas valve is energized when the control has commanded it offSafety fault
E08The flame current the control reads is low but still high enough to keep runningWarning
E09The inducer limit switch or the condensate pressure switch is openSoft lockout
E11Gas valve relay faultSafety fault
E12The fuse on the integrated furnace control has opened, so 24 volt control power is lostHard lockout

American Standard furnace Flashing Slow: Normal standby

StatusShown as: Red LED flashing slowly and steadily

Normal standby. The control board is powered and healthy and the thermostat is not calling for heat.

Manual wording: “Flashing Slow --- Normal - No call for Heat”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Normal operation with no heat call from the thermostat

What you can safely check yourself

  • Check the thermostat - make sure it is set to Heat and set higher than room temperature
  • Check thermostat batteries if it has them

When to call a technician

No service needed. If the thermostat is calling for heat and the LED stays on the slow flash, the heat call is not reaching the furnace and a technician should check the thermostat and its wiring.

Sources

American Standard furnace Flashing Fast: Normal operation with an active call for heat

StatusShown as: Red LED flashing rapidly and steadily

Normal operation with an active call for heat. The control has accepted the thermostat's heat request.

Manual wording: “Flashing Fast --- Normal - Call for Heat”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Normal operation during a heating cycle

When to call a technician

No service needed. If the LED flashes fast but no warm air arrives, note whether it changes to a fault code and have a technician diagnose it.

Sources

American Standard furnace Continuous ON: The integrated furnace control

Hard lockoutShown as: LED on solid, never blinking

The integrated furnace control (IFC) has failed. The manual's instruction for a solid LED is to replace the control board.

Manual wording: “Continuous ON --- Replace IFC”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Failed integrated furnace control board

What you can safely check yourself

  • Turn the furnace switch off and back on once to confirm the LED really stays solid rather than flashing a code

When to call a technician

This is a board replacement. Call a technician.

Sources

American Standard furnace Continuous OFF: The control board is not receiving power

WarningShown as: LED completely dark

The control board is not receiving power. The manual's instruction for a dark LED is to check power to the furnace.

Manual wording: “Continuous OFF --- Check Power”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. No line power reaching the furnace
  2. Open circuit breaker or blown fuse
  3. Furnace disconnect switch off
  4. Blower door not fully seated, which opens the door switch and cuts power to the blower and gas valve

What you can safely check yourself

  • Check the breaker in your electrical panel and reset it if it is tripped
  • Check that the furnace switch is turned on - it is usually near the furnace, by the basement stairs, or in the ceiling
  • Make sure the furnace door is on properly and fully latched, especially after a filter change

When to call a technician

If the breaker and switch are on and the door is closed but the board is still dark, a technician needs to check the transformer, fuse, and wiring.

Sources

American Standard furnace 2 Flashes: System lockout

Hard lockoutShown as: 2 flashes, pause, repeat

System lockout. The control tried and failed to establish or hold a flame enough times (retries or recycles exceeded) and has shut the furnace down.

Manual wording: “2 Flashes --- System Lockout (Retries or Recycles exceeded)”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Loss of flame or gas supply failure - the control module retries the ignition sequence up to two times after the sensor cools, and if ignition is not achieved it will lockout the furnace
  2. Ignition failure at the burners
  3. Flame lost repeatedly during the heating cycle

What you can safely check yourself

  • Check that other gas appliances in the house work, which tells you whether gas is reaching the home
  • Check the thermostat is set to Heat and above room temperature
  • Reset once by turning the furnace switch off and back on

When to call a technician

If the furnace locks out again after one reset, stop resetting it. Repeated ignition failure means the igniter, flame sensor, gas valve, or gas pressure needs a technician.

Sources

American Standard furnace 3 Flashes: Draft pressure error

Soft lockoutShown as: 3 flashes, pause, repeat

Draft pressure error. The pressure switch that proves the draft inducer is moving flue gas is not in the state the control expects, so the control will not open the gas valve.

Manual wording: “3 Flashes --- Draft Pressure Error - Possible problems: a) Venting problem b) Pressure switch problem c) Inducer problem”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Venting problem
  2. Pressure switch problem
  3. Inducer problem
  4. Excessive combustion vent pressure or flue blockage
  5. Induced draft blower failure - if pressure is not sensed by the pressure switch it will not allow the gas valve to open, therefore the unit will not start

What you can safely check yourself

  • Look for blockage - check whether snow, ice, weeds, grass, leaves, or a nest is blocking the furnace venting outside
  • On a 90%+ condensing model, check the condensate drain line and trap for a clog and check that any condensate pump is working
  • Make sure the furnace door is on properly

When to call a technician

If the venting is clear, the pressure switch, its tubing, or the inducer motor needs a technician. Never jumper or bypass a pressure switch.

Sources

American Standard furnace 4 Flashes: Open temperature limit circuit

Soft lockoutShown as: 4 flashes, pause, repeat

Open temperature limit circuit. A temperature limit switch has opened because the furnace got too hot, which closes the gas valve and stops the burners.

Manual wording: “4 Flashes --- Open Temperature Limit Circuit”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Open temperature limit circuit
  2. Restricted airflow across the heat exchanger - the manual's own limit checkout deliberately trips the limit by restricting the airflow at the return
  3. Flame roll-out device tripped: all models have a thermal control device on the burner cover and 'in case of flame roll-out, the device will cause the circuit to open which shuts off all flow of gas'

What you can safely check yourself

  • Change your filter - a dirty filter can cause your furnace to stop working
  • Check that supply registers and return grilles are open and unblocked
  • Make sure the furnace door is on properly after changing the filter, as this can prevent the furnace from starting
  • Look for snow, ice, weeds, or grass blocking the furnace venting

When to call a technician

If the code returns after a clean filter and open vents, call a technician. A tripped flame roll-out device in particular means combustion gas escaped the burner box and must be diagnosed before the furnace is run again. Never reset or bypass a limit or roll-out switch yourself.

Sources

American Standard furnace 5 Flashes: Flame is being detected when there should be no flame present

Safety faultShown as: 5 flashes, pause, repeat

Flame is being detected when there should be no flame present.

Manual wording: “5 Flashes --- Flame sensed when no flame should be present”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Flame sensed when no flame should be present
  2. Gas valve leaking through or slow to close
  3. Flame sensing circuit fault

What you can safely check yourself

  • Turn the furnace switch off and leave it off
  • If you smell gas, leave the house and call the gas utility from outside

When to call a technician

Call a technician. A flame signal with the gas valve off points at the gas valve or flame-proving circuit and is not a homeowner repair.

Sources

American Standard furnace 6 Flashes: The 115 volt AC line and neutral are reversed at the furnace, the furnace is poorly grounded, or supply voltage is too low

WarningShown as: 6 flashes, pause, repeat

The 115 volt AC line and neutral are reversed at the furnace, the furnace is poorly grounded, or supply voltage is too low.

Manual wording: “6 Flashes --- 115 volt AC power reversed, poor grounding or system voltage too low”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. 115 volt AC power reversed
  2. Poor grounding
  3. System voltage too low

What you can safely check yourself

  • Note whether the code appeared right after electrical work, a new outlet, or use of a generator
  • Check whether lights elsewhere in the house are dimming, which suggests a low-voltage supply problem

When to call a technician

Call a technician or electrician. Correcting line polarity, grounding, or a low-voltage supply is electrical work at the furnace and the panel.

Sources

American Standard furnace 7 Flashes: Gas valve circuit error

Safety faultShown as: 7 flashes, pause, repeat

Gas valve circuit error. The control has detected a fault in the circuit that drives the gas valve.

Manual wording: “7 Flashes --- Gas valve circuit error”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Gas valve circuit error

What you can safely check yourself

  • Turn the furnace switch off and leave it off until a technician has looked at it

When to call a technician

Call a technician. Anything involving the gas valve or its wiring is a licensed-tech job.

Sources

American Standard furnace 8 Flashes: Low flame sense signal

WarningShown as: 8 flashes, pause, repeat

Low flame sense signal. The furnace is running but the flame current the control reads is weak.

Manual wording: “8 Flashes --- Low flame sense signal”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Low flame sense signal

What you can safely check yourself

  • Note whether the furnace is still heating; this code usually appears while it is still running

When to call a technician

Schedule service. A weak flame signal usually means the flame sensor needs cleaning or the burner flame is not right, and if it drops further the furnace will lock out. Cleaning a flame sensor means working in the burner compartment, so leave it to a technician.

Sources

American Standard furnace 9 Flashes: The control is directing the technician to check the igniter circuit and the voltage between line neutral and 24VAC common, which points at an igniter or grounding problem

WarningShown as: 9 flashes, pause, repeat

The control is directing the technician to check the igniter circuit and the voltage between line neutral and 24VAC common, which points at an igniter or grounding problem.

Manual wording: “9 Flashes --- Check Ignitor Circuit and Line "N" to 24VAC "Common" voltage ( 2 volts) [possible grounding problem]”

Documented for: *UD1 / *DD1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. Igniter circuit fault
  2. Possible grounding problem (Line "N" to 24VAC "Common" voltage should be at or under 2 volts)

What you can safely check yourself

  • Note whether the furnace tries to start and never lights

When to call a technician

Call a technician. Checking the igniter circuit and neutral-to-common voltage requires meters inside a live control compartment.

Source

American Standard furnace code E01: Internal integrated furnace control failure

Hard lockout

Internal integrated furnace control failure. The control's own processor has lost its interrupt or hit another internal error.

Manual wording: “Loss of the IRQ or other internal failures (Internal IFC error)”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Loss of the IRQ or other internal failures (Internal IFC error)

What you can safely check yourself

  • Turn the furnace switch off, wait a minute, and turn it back on once to see whether the code clears

When to call a technician

If E01 returns, the control board needs to be replaced by a technician.

Sources

American Standard furnace code E2.1: Retry exceeded

Hard lockout

Retry exceeded. The furnace tried to light and never proved a flame, so the control has locked out for one hour.

Manual wording: “Retry Exceeded (Flame never sensed, one hour lockout after 6 times)”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Flame never sensed on repeated ignition attempts
  2. No gas or interrupted gas supply
  3. Failed igniter
  4. Dirty or failed flame sensor

What you can safely check yourself

  • Check that other gas appliances in the house work, which tells you gas is reaching the home
  • Check the thermostat is set to Heat and above room temperature
  • Reset once by turning the furnace switch off and back on

When to call a technician

If the furnace locks out again, stop resetting it. Repeated failure to light needs a technician to check the igniter, flame sensor, gas valve, and gas pressure.

Sources

American Standard furnace code E2.2: Recycles exceeded

Hard lockout

Recycles exceeded. The burner lit but the flame was lost during the cycle, ten times, so the control locked out for one hour.

Manual wording: “Recycles Exceeded (Flame sensed then lost, one hour lockout after 10 times)”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Flame sensed then lost, ten times
  2. Marginal flame signal or dirty flame sensor
  3. Low or unstable gas pressure
  4. Restricted venting causing the burner to be starved

What you can safely check yourself

  • Change your filter if it is dirty
  • Look for snow, ice, weeds, or grass blocking the furnace venting
  • Reset once by turning the furnace switch off and back on

When to call a technician

Repeated flame loss is a burner, flame sensor, gas pressure, or venting problem. Have a technician diagnose it rather than resetting repeatedly.

Sources

American Standard furnace code E2.3: The control commanded the gas valve on and the valve did not energize, ten times in a row

Hard lockout

The control commanded the gas valve on and the valve did not energize, ten times in a row.

Manual wording: “Gas Valve Not Energized When It Should Be exceeded after 10 times”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Gas valve not energized when it should be
  2. Gas valve or gas valve wiring fault
  3. Control board output fault

When to call a technician

This is a gas valve or control board fault. Call a technician; never work on a gas valve or its wiring yourself.

Sources

American Standard furnace code E3.1: The pressure switch is reading closed when the control expects it to be open, which the control calls a shorted pressure switch

Soft lockout

The pressure switch is reading closed when the control expects it to be open, which the control calls a shorted pressure switch.

Manual wording: “Shorted Pressure Switch”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Shorted pressure switch
  2. Pressure switch contacts stuck closed
  3. Wiring fault across the pressure switch

When to call a technician

A stuck pressure switch is a safety-proving device. It must be tested and replaced by a technician, never jumpered.

Sources

American Standard furnace code E3.2: The pressure switch will not close, so the control cannot prove the draft inducer is moving flue gas and will not open the gas valve

Soft lockout

The pressure switch will not close, so the control cannot prove the draft inducer is moving flue gas and will not open the gas valve.

Manual wording: “Open Pressure Switch”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Open pressure switch
  2. Blocked or restricted vent or combustion air piping
  3. Condensate backing up in the drain or trap (condensing models)
  4. Draft inducer not running or running weak
  5. Pressure switch tubing disconnected or plugged

What you can safely check yourself

  • Look for blockage - snow, ice, weeds, grass, leaves, or a nest in the furnace venting outside
  • On the A951X and other 95% condensing models, check the condensate drain line and trap for a clog and check that any condensate pump is working
  • Make sure the furnace door is on properly

When to call a technician

If the venting and drain are clear, the pressure switch, its tubing, or the inducer needs a technician. Do not jumper the pressure switch.

Sources

American Standard furnace code E04: A safety limit has opened: the main thermal limit, a flame rollout switch, or the reverse airflow switch

Safety fault

A safety limit has opened: the main thermal limit, a flame rollout switch, or the reverse airflow switch. The furnace has stopped heating.

Manual wording: “Open Limit (Main Thermal, Rollout Switch, or Reverse Airflow Switch)”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Open limit (main thermal, rollout switch, or reverse airflow switch)
  2. Restricted airflow across the heat exchanger from a dirty filter or blocked returns
  3. Blocked venting
  4. Flame rollout, which indicates a blocked heat exchanger or burner problem

What you can safely check yourself

  • Change your filter - a dirty filter can cause your furnace to stop working
  • Check that supply registers and return grilles are open and unblocked
  • Look for snow, ice, weeds, or grass blocking the furnace venting
  • Make sure the furnace door is on properly after changing the filter

When to call a technician

If the code returns after a clean filter and open vents, call a technician. A tripped rollout switch means combustion gases came out of the burner box and must be diagnosed before the furnace runs again. Never reset or bypass a rollout or limit switch yourself.

Sources

American Standard furnace code E05: The control is sensing a flame when there should not be one - for example with the gas valve commanded off

Safety fault

The control is sensing a flame when there should not be one - for example with the gas valve commanded off.

Manual wording: “Flame detected, should not be present”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Flame detected, should not be present
  2. Gas valve leaking through or slow to close
  3. Flame sensing circuit fault

What you can safely check yourself

  • Turn the furnace switch off and leave it off
  • If you smell gas, leave the house and call the gas utility from outside

When to call a technician

Call a technician. A flame signal with the valve off points at the gas valve and is a safety issue.

Sources

American Standard furnace code E6.1: Line and neutral are reversed in the 115 volt supply to the furnace

Warning

Line and neutral are reversed in the 115 volt supply to the furnace.

Manual wording: “Voltage reversed polarity”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Voltage reversed polarity

What you can safely check yourself

  • Note whether the code appeared right after electrical work or a new circuit was run

When to call a technician

Call a technician or electrician to correct polarity at the furnace circuit.

Sources

American Standard furnace code E6.2: The furnace does not have a good electrical ground, which the control needs in order to sense flame reliably

Warning

The furnace does not have a good electrical ground, which the control needs in order to sense flame reliably.

Manual wording: “Bad grounding”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Bad grounding

When to call a technician

Call a technician or electrician. Correcting the ground path is electrical work inside the furnace.

Sources

American Standard furnace code E6.3: Igniter fault

Hard lockout

Igniter fault. Either the igniter relay on the control has failed or the igniter itself is open (burned out).

Manual wording: “(1) Igniter relay fails (2) Igniter open”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Igniter relay fails
  2. Igniter open

What you can safely check yourself

  • Turn the furnace switch off and back on once to see whether the furnace attempts to light

When to call a technician

Call a technician. A hot surface igniter is fragile and lives in the burner compartment; replacing it or the control board is not a homeowner job.

Sources

American Standard furnace code E7.1: The gas valve is energized when the control has commanded it off

Safety fault

The gas valve is energized when the control has commanded it off.

Manual wording: “Gas valve (MVL) is energized when it should be off”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Gas valve (MVL) is energized when it should be off
  2. Gas valve relay stuck closed on the control board

What you can safely check yourself

  • Turn the furnace switch off and leave it off until a technician has looked at it

When to call a technician

Call a technician. A gas valve energized without a command is a safety fault involving the gas valve circuit.

Sources

American Standard furnace code E08: The flame current the control reads is low but still high enough to keep running

Warning

The flame current the control reads is low but still high enough to keep running. This is an early warning, not a shutdown.

Manual wording: “Flame current is low, but still strong enough to allow operation”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Flame current is low, but still strong enough to allow operation
  2. Dirty or degraded flame sensor
  3. Weak or poorly positioned burner flame
  4. Marginal grounding

What you can safely check yourself

  • Note that the furnace is likely still heating; schedule service rather than treating it as an emergency

When to call a technician

Schedule service before it turns into an ignition lockout. Cleaning or repositioning a flame sensor means opening the burner compartment, which is a technician's job.

Sources

American Standard furnace code E09: The inducer limit switch or the condensate pressure switch is open

Soft lockout

The inducer limit switch or the condensate pressure switch is open. On a condensing furnace this most often means condensate is backing up.

Manual wording: “Open Inducer Limit Switch or Condensate Pressure Switch”

Documented for: A951X single-stage condensing furnaces

Likely causes, most common first

  1. Open inducer limit switch or condensate pressure switch
  2. Blocked condensate drain, trap, or hose
  3. Frozen condensate in a drain line running through a cold space
  4. Full or failed condensate pump
  5. Inducer overheating

What you can safely check yourself

  • Check the condensate drain line and trap for a clog
  • Check that any condensate pump is plugged in, not full, and pumping
  • In freezing weather, check whether any part of the drain line runs somewhere cold enough to freeze

When to call a technician

If the drain and pump are clear, the inducer limit or condensate switch needs a technician. Do not bypass either switch.

Source

American Standard furnace code E11: Gas valve relay fault

Safety fault

Gas valve relay fault. The control has found the gas valve output in the wrong state - either not energizing when commanded, or a relay stuck closed.

Manual wording: “Gas valve not energized when it should be / Gas valve relay stuck closed”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Gas valve not energized when it should be
  2. Gas valve relay stuck closed

What you can safely check yourself

  • Turn the furnace switch off and leave it off until a technician has looked at it

When to call a technician

Call a technician. A stuck gas valve relay is a safety fault and normally means replacing the integrated furnace control.

Sources

American Standard furnace code E12: The fuse on the integrated furnace control has opened, so 24 volt control power is lost

Hard lockout

The fuse on the integrated furnace control has opened, so 24 volt control power is lost.

Manual wording: “Open fuse”

Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display

Likely causes, most common first

  1. Open fuse
  2. Short in the low-voltage thermostat or accessory wiring
  3. Short in a control circuit component

What you can safely check yourself

  • Note whether the code appeared right after a thermostat was replaced or new low-voltage wiring was run, and mention that to the technician

When to call a technician

Call a technician. The fuse blew because something shorted; replacing it without finding the short will just blow it again.

Sources

How old is this American Standard?

Age changes what a fault code means for you. The same failure is a routine repair on a six-year-old unit and the end of the line on a twenty-year-old one. Your American Standard serial number has the build date in it.

Decode your American Standardserial number →

Manuals used for this page