American Standard Furnace Code E2.1
Hard lockout
Retry exceeded. The furnace tried to light and never proved a flame, so the control has locked out for one hour.
Manual wording: “Retry Exceeded (Flame never sensed, one hour lockout after 6 times)”
Documented for: A951X condensing and A801X induced draft furnaces with the seven-segment IFC display
Likely causes, most common first
- Flame never sensed on repeated ignition attempts
- No gas or interrupted gas supply
- Failed igniter
- Dirty or failed flame sensor
What you can safely check yourself
- Check that other gas appliances in the house work, which tells you 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, stop resetting it. Repeated failure to light needs a technician to check the igniter, flame sensor, gas valve, and gas pressure.
A American Standard furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installer's Guide - Upflow/Horizontal and Dedicated Downflow Gas-Fired, Direct/Non-Direct Vent, Single Stage Condensing Furnaces with High Efficiency Motor (88-A951X001-1D-EN) (American Standard Heating and Air Conditioning, A951X040BU3SAB through A951X120DD5SAB single-stage 95% condensing furnaces (Silver 95 family)) · checked 2026-08-25
- Installer's Guide - Upflow/Downflow/Horizontal Left/Right Gas-Fired, Single Stage Induced Draft Furnaces with High Efficiency Motor (88-A801X003-1C-EN) (American Standard Heating and Air Conditioning, A801X026AM2SC through A801X120DM5SC single-stage 80% induced draft furnaces (Silver 80 family)) · checked 2026-08-25