American Standard Furnace 6 Flashes: What It Means & How to Fix It
Compiled & reviewed by the HVAC Flash Codes editorial team · Updated 2026-08-28 · confidence: high
⛔ Stop — call a licensed pro
What does American Standard furnace 6 flashes mean?
Flame sensed when no flame should be present — the control detects a flame signal when none should exist. Most often caused by Gas valve leaking through / not fully closing.
What your furnace LED does. The diagnostic light blinks 6 flashes, pause, repeat — that pattern is American Standard furnace 6 flashes.
What American Standard furnace 6 flashes means
Flame sensed when no flame should be present — the control detects a flame signal when none should exist.
Common causes
Gas valve leaking through / not fully closing
Flame sensor or control board fault
Slow-to-extinguish flame
Homeowner-safe steps to try
Turn the thermostat to OFF and watch whether the furnace shuts down as expected
Power-cycle the furnace once at the breaker
When to call a licensed HVAC technician
If the basic checks below don't clear the code, the fault recurs, or anything involves the gas valve, burners, flame sensor or wiring, stop and book a licensed HVAC technician. Repairs to the combustion or gas system are not DIY.
⚠️ Safety first. Gas furnaces burn fuel and produce combustion gases. If you ever smell gas (a rotten-egg or sulfur odor), hear hissing, or your carbon-monoxide alarm sounds, do not touch light switches, thermostats, or the furnace — leave the home immediately and call your gas utility's emergency line or 911 from outside. Homeowners should limit themselves to simple, safe steps: setting the thermostat, checking and replacing the air filter, confirming the furnace switch and breaker are on, keeping supply registers and return grilles open, and clearing snow, ice, or debris from outdoor vent and intake terminations. Never bypass, jumper, or reset safety switches (limit, flame-rollout, or pressure switches), never open the gas valve or burner compartment, and never attempt combustion, electrical, or control-board repairs yourself. Error codes point toward a problem but are not a substitute for proper diagnosis — when in doubt, turn the system off and call a licensed HVAC technician. Keep working carbon-monoxide detectors on every level of your home.
When to call a pro: This is a gas-safety fault involving the gas valve and flame-proving circuit — call a licensed HVAC technician promptly and do not attempt repairs. If you smell gas, leave the home and call your gas utility or 911 from outside.
American Standard furnace 6 flashes FAQ
What does American Standard furnace 6 flashes mean?
Flame sensed when no flame should be present — the control detects a flame signal when none should exist.
What causes American Standard furnace 6 flashes?
Common causes: Gas valve leaking through / not fully closing; Flame sensor or control board fault; Slow-to-extinguish flame.
Can I fix American Standard furnace 6 flashes myself?
You can safely try: Turn the thermostat to OFF and watch whether the furnace shuts down as expected; Power-cycle the furnace once at the breaker. This is a gas-safety fault involving the gas valve and flame-proving circuit — call a licensed HVAC technician promptly and do not attempt repairs. If you smell gas, leave the home and call your gas utility or 911 from outside.
Sources: manualslib.com. General information for homeowners, not professional advice — confirm against your furnace's manual and a licensed technician.