HVAC Code Lookup

American Standard Furnace 2 Flashes

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.

A American Standard furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other American Standard codes