Furnace Fault Codes

Furnace flashing 2 times: what 2 flashes means

The number of flashes on a furnace control board is not a standard. Every manufacturer assigns its own meanings, and 2 flashes means something different across the 8 control families below.

On an Armstrong it is improper earth ground, on a Goodman it is pressure switch is closed when it should be open, and on a Heil it is low pressure switch closed when it should be open.

That's three separate problems sharing the same count of two, not one fault with minor variations — the number alone gets you nowhere. Confirm which brand you have before doing anything about it.

Some of the faults listed here are gas-safety faults. Those ones involve the gas valve, the burner compartment, or the heat exchanger — the parts whose failure can put combustion products, including carbon monoxide, into the air the house breathes, and each carries this warning on its own page. Do not keep resetting a furnace that reports one of them in order to hold the heat on. Have it looked at by a licensed technician, and make sure there is a working carbon monoxide alarm on every level of the home, including the level the furnace is on. The conditions that mean stop now.

2 flashes, by manufacturer

Furnace brandWhat 2 means there
Armstrong
2 flashes		Improper earth ground
Goodman
2 flashes — Goodman GMS, GMP, GMH, GMV8, GMV9 and Amana AMH, AMV9 series		Pressure switch is closed when it should be open
Goodman
2 red flashes — GMEC96 / AMEC96		Pressure switch stuck closed, or an inducer error
Goodman
2 amber flashes — GMEC96 / AMEC96		Normal operation — second stage heat
Goodman
2 green flashes — GMEC96 / AMEC96		Normal operation — high stage or single stage cooling
Heil
2 flashes		Low pressure switch closed when it should be open
Rheem
*RC 92+ / *RL 90+		Pressure switch did not close within 10 seconds
Rheem
Rheem standard gas furnaces		Pressure switch failure — switch remains open
Trane
2 flashes		System lockout — retries or recycles exceeded
York
2 red flashes — UTEC / ST		Pressure switch stuck closed, or an inducer error
York
2 amber flashes — UTEC / ST		Normal operation with a call for second stage heat

Before counting again

Don't mistake a continuous blink for two flashes: an even glow that never pauses is the board's heartbeat, meaning simply that it's powered up and has nothing to report. Patterns that aren't faults, listed by brand, are catalogued separately.

Finding out which brand you have

Thermostats don't carry the brand name; the rating plate mounted inside the cabinet does, and it often names a company different from the one that built the control board itself. This guide to reading a furnace fault code walks through finding that plate and handling displays that show a number instead of flash counts.

Other flash counts

What the fix costs

Once a technician traces the fault to a specific part, cost is the next question: typical control board replacement cost covers that job specifically, while the furnace repair cost guide covers service calls generally.

What 2 flashes usually points to

2 flashes is dominated by the pressure switch: Goodman, Heil and York all report it stuck closed before the inducer proves draft, and Rheem's *RC/*RL board reports the opposite failure, the switch not closing at all. Armstrong is the outlier, using 2 flashes for a grounding problem instead. Either way, the switch, its tubing, and the inducer motor are worth checking before the ignitor or gas valve. That is a shift from 1 flash's mix of wiring and ignition faults, and it flips direction again at 3 flashes, where the same pressure switch is reported stuck open instead of stuck closed.

Sources

The two-flash interpretations listed here are taken from the manufacturer literature cited on each code page:

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.