Furnace locks out with A01 on display, burner does not ignite, fan may run briefly then stop

Safety first: Turn off electrical power to the furnace and close the gas shutoff valve before opening the cabinet. Wait for all hot surfaces to cool.

• Check gas supply: Verify the main gas cock to the Beretta furnace is open and that other gas appliances in the home work. If there is no gas, contact your gas supplier.
• Inspect burner area: Remove the burner access panel. Look for heavy dust, rust flakes, or debris on the burner and around the ignition electrode and ionization probe. Gently vacuum loose debris and clean metal surfaces with a soft brush.
• Clean ignition electrode and flame sensor: Remove the ignition electrode/ionization probe assembly (usually held by 1–2 screws). Lightly clean the metal rod with fine abrasive pad (Scotch-Brite) or very fine sandpaper. Do not bend the rod. Reinstall, ensuring the ceramic insulator is not cracked and the gap/position relative to the burner is as per Beretta specifications.
• Check wiring: Inspect the ignition cable and flame sensor wire from the electrode to the Beretta control board for burns, cuts, or loose connectors. Reseat all push-on connectors firmly.
• Reset the lockout: Restore power and gas, then follow the Beretta user manual to reset the A01 lockout (usually by pressing the reset button on the control panel for a few seconds). Observe ignition: if there is no spark or no flame, shut down and call a qualified technician.

Do not attempt to adjust or replace the gas valve or modify gas piping yourself; this must be done by a licensed gas technician.