The short answer
An American Standard furnace error code names the safety check that shut your heat off, and the quickest way to read one is by what the furnace is doing. In Northern Virginia homes the usual three are: it tries to light and can’t (E3.2, a pressure switch code that usually means a vent or drain problem), it lights and drops out (E2.2 or E08, usually a dirty flame sensor), or it overheats (E04, usually a clogged filter). Newer American Standard furnaces show the code on a small display through the door window; older ones blink a red light. Change the filter, check the drain, power cycle once, and call if the code returns.
Where to find the code
Look through the small window in the lower door. Newer American Standard gas furnaces, including the Gold S9X2 and the Silver S9X1, have a little display on the control board. Normal reads IdL (idle), Ht1 or Ht2 (heating) or CL1 (cooling). A problem shows as a code starting with E, flashing back and forth with the status.
Older American Standard furnaces have a red light and a green light on the board instead of a display. The red one blinks a count. Count it a few times, then match it to the chart printed inside the door. If the code is on the wall thermostat rather than the furnace, those alerts are in our American Standard thermostat and heat pump code guide.
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It tries to light but never does
Codes: E3.2 (E3.4 on the second stage of an S9X2), E2.1, or 3 or 2 blinks on older boards.
You hear the small inducer fan start near the top of the furnace, then nothing. Before it lights, the furnace has to prove the vent is clear: the inducer pulls air and a pressure switch closes. E3.2 means that switch never closed. The usual reasons are a vent pipe blocked by leaves, a nest or snow, a backed up condensate trap or drain line, a split hose on the switch, or a tired inducer motor. E2.1 is different: the furnace tried to light three times and never saw a flame, which points to the igniter, the gas supply or the flame sensor. It then waits an hour before trying again.
Try first: clear the white PVC pipes where they leave the house, look for standing water in the drain, make sure the gas valve handle next to the furnace runs in line with the pipe, then power cycle once.
It lights, then shuts off
Codes: E2.2, E08, or 2 or 8 blinks.
The burners light for a few seconds and go out, over and over. A small rod in the flame, the flame sensor, tells the board the fire is lit. When it gets coated it reads weak (E08), and eventually the board gives up (E2.2, locked out for an hour after ten tries). A short cleaning fixes it most of the time. If it keeps coming back, something is dirtying it, and the venting and combustion should be checked. A furnace that runs a while and then shuts off is a different problem; furnace short cycling covers that.
The blower runs, but the air is cool
Codes: E04, or 4 blinks.
The burners shut off because the furnace got too hot, and the blower keeps going to cool it down. That’s a limit switch, and most of the time the cause is airflow: a clogged filter, a lot of closed vents, or a blower that’s slowing down. Change the filter first. E04 also covers the rollout switches near the burners. If one of those has a popped red button, don’t reset it yourself. Flame rolled out of the burner box, and that needs a tech. More on a furnace blowing cold air.
Water around the furnace and no heat
Codes: E09, or a 3 blink pressure code.
High-efficiency furnaces make water as they burn and drain it away. When the trap, the drain line or the condensate pump backs up, a switch shuts the furnace down before it floods. Check the pump’s tank: if it’s full and humming, the pump has quit. A clogged trap is a cleaning; a dead pump is a part.
The display is dark
Codes: none, or E12.
No display and no lights usually means no power. Check the furnace switch and the breaker, and push the lower door fully closed, because a door switch cuts the power when it’s off. E12 means the small fuse on the board blew, most often from a short in the thermostat wiring. A new fuse without finding the short just blows again.
Codes that mean shut it off now
E05 (flame where there shouldn’t be one) and E7.1 (gas valve powered when it should be off), or 5 and 7 blinks on older boards, mean gas could be flowing when the furnace isn’t asking for it. Turn the furnace off at its switch and close the gas valve by turning the handle across the pipe. If you smell gas, don’t touch any switches: leave the house and call your gas company from outside. If the CO alarm is sounding, here is what to do.
Every American Standard furnace E code
From the manufacturer’s manual for the S-series gas furnaces, which American Standard shares with Trane.
Swipe to see all columns →
Swipe to see all columns →
| Code | What it means |
|---|---|
| E01 | The control board failed its own self check |
| E2.1 | No flame after three tries to light; locks out for an hour |
| E2.2 | Flame lit, then was lost, ten times; locks out for an hour |
| E2.3 | First stage gas valve didn’t open when it should have |
| E3.1 | First stage pressure switch closed when it should be open |
| E3.2 | First stage pressure switch didn’t close: vent, drain or inducer |
| E3.3 / E3.4 | The same two faults on the second stage switch (S9X2 only) |
| E04 | A limit switch opened: overheating, low airflow or a rollout switch |
| E05 | Flame sensed when the gas should be off. Shut off the gas |
| E6.1 | Power polarity reversed |
| E6.2 | Poor ground |
| E6.3 | Igniter circuit open, or its relay failed |
| E7.1 | Gas valve powered when it should be off. Shut off the gas |
| E08 | Flame signal weak but still running, usually a dirty flame sensor |
| E09 | Inducer limit or condensate pressure switch open, usually a backed up drain |
| E11 | Gas valve or gas valve relay fault |
| E12 | The board’s fuse blew, usually a short in the thermostat wiring |
| E14, E18 | Listed in the manufacturer’s troubleshooting chart; a tech reads these |
On older boards with a red light, 2 blinks is a lockout, 3 is the pressure switch, 4 is a limit, 5 and 7 mean shut off the gas, 6 is power polarity or ground, and 8 is a weak flame signal. The chart inside your door has the final word, because some older models use a three-light board.
How to reset it, and when not to
Set the thermostat to off. Turn off the breaker or the switch for the equipment, wait about five minutes, turn it back on and set the thermostat back. Do it once. That clears an hour-long lockout. Before you do, write the code down, and on a furnace with a display press Menu until L6F shows, then Option, to read the last six faults. Leave that history for the tech. If the same code comes back after one reset, more resets won’t help.
Is a code a sign of a bad furnace?
No. A code means a safety did its job. American Standard is built by the same company as Trane, on the same boards, and our take on whether American Standard is a good brand is yes. Most of these codes end in a small part or a cleaning. Our American Standard repair page lists the common repairs and their usual range. Own a Trane? The Trane furnace code guide lists the same codes by number.
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Book an American Standard repair
Call (703) 997-9757 or book online. A diagnostic visit is $99, and the tech reads the code, finds the part that set it and gives you the price before any work starts. We answer day or night. Our heating check is $67 per system, through December 31: furnace, heat pump or boiler. If someone already quoted you a new system, our free second opinion looks at it first. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What does E3.2 mean on an American Standard furnace?
E3.2 means the first stage pressure switch didn’t close, so the furnace won’t light. It’s usually a blocked vent pipe, a backed up condensate trap or drain, a split hose on the switch or a weak inducer motor, not the switch itself.
Why does my American Standard furnace light and then shut off?
Usually a dirty flame sensor. The board can’t confirm the flame, so it shuts the gas off, and after ten tries it shows E2.2 and locks out for an hour. E08 is the early warning of the same thing.
How do I reset an American Standard furnace?
Set the thermostat to off, turn off the furnace switch or breaker for about five minutes, turn it back on and set the thermostat to heat. Do it once. If the code returns, the furnace needs a repair.
Are American Standard and Trane furnace codes the same?
Yes. Both brands are built by Trane Technologies, and furnaces in the same model series, such as the S9X1, S9X2 and S9B1, show the same E codes on the same control boards.
What does a blinking red light on an American Standard furnace mean?
It’s an error count. Count the blinks and match the number to the chart inside the furnace door. Three blinks is usually the pressure switch, four is overheating, and five or seven mean shut off the gas and call.
Can I fix an American Standard furnace code myself?
Some. Changing a dirty filter, clearing a blocked vent pipe outside, emptying a full condensate pump tank and one power cycle are fine for a homeowner. Igniters, flame sensors, gas valves, rollout switches and control boards are a technician’s job.
