American Standard AUH1B080A9H31A Error Code 2 Flashes: System Lockout (Retries or Recycles Exceeded)

What Does Code 2 Flashes Mean?

Code 2 (2 Flashes) on the White-Rodgers 50A65 Integrated Furnace Control (IFC) means the American Standard AUH1B080A9H31A has entered a system lockout — it exhausted all of its ignition retries or recycles and shut down as a safety measure. The furnace will not fire again until the lockout is cleared.

On each attempt the board runs the full single-stage sequence: inducer on, pressure switch closed, hot surface igniter glowing, single gas valve open, and the flame sensor looking for a proven flame. A lockout is the end state of that sequence failing repeatedly — either the burners never lit, or they lit and the flame was then lost. In that sense the 2-flash code is downstream of the more specific codes on the same board: a chronically weak signal that shows as an 8-flash (low flame sense) can decay into flame dropouts and end in lockout, a failing igniter shows as a 9-flash, and a venting problem shows as a 3-flash before ignition is even attempted.

Because the 2-flash code is a lockout rather than a single-component fault, resetting only clears the latch — it does not fix the root cause. Cycling power off for about 30 seconds and back on (using the furnace switch or breaker) is a safe one-time reset a homeowner can perform. If the furnace lights and runs normally afterward, a transient event such as a brief gas interruption may have been to blame. If it locks out again, the underlying cause — most often a fouled flame sensor, and commonly a worn igniter — needs a technician, because the actual repairs (flame-sensor service inside the burner area to a fault level, igniter replacement, or gas-supply diagnosis) go beyond safe homeowner work on this model.

What You'll Notice

• The furnace attempts to start several times — you may hear the inducer and see the igniter glow — then goes silent and stops trying.
• The diagnostic LED shows a repeating group of 2 flashes.
• No heat is produced and the furnace stays locked out until power is cycled.
• The burners may light briefly and then go out before the blower delivers sustained heat.

Common Causes

How This Is Diagnosed

A technician works backward from the lockout to the step that keeps failing. First they confirm gas is actually reaching the furnace (supply valve open, gas to other appliances). Then, during a monitored ignition attempt, they watch the sequence: if the igniter glows and the burners light but the flame signal is too weak or drops out, the flame sensor's microamp output is measured and the sensor cleaned or replaced; if the igniter never glows, the igniter and its circuit are tested (the 9-flash territory); if the sequence never gets past draft, the pressure switch and venting are checked (the 3-flash territory). The number of failed retries before lockout helps point to whether the flame is never established or is being lost after ignition.

When to Call a Professional

This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:

• The furnace locks out again after a single power-cycle reset
• The igniter does not glow, or the burners light and then repeatedly go out within seconds
• You can smell gas but the burners will not stay lit
• The furnace has been locking out intermittently for several days, suggesting a degrading igniter or flame sensor

✓ Verified against manufacturer service manual — March 2026