Furnace attempts to start but shuts down quickly, control shows E02, no sustained flame.

Safety: Switch off power and close the gas valve before working inside the furnace.

Steps:

• Locate the flame sensor: It is a small metal rod on a porcelain insulator positioned in front of one of the burners and wired back to the Atlantic control board.
• Clean the flame sensor: Remove the mounting screw and gently pull out the sensor. Lightly polish the metal rod with fine steel wool or a non-abrasive scouring pad to remove oxidation. Do not sand the porcelain. Wipe with a clean dry cloth and reinstall.
• Check burner flame: Restore power and gas, call for heat, and observe through the sight glass. The flame should be steady and blue, fully engulfing the flame sensor. Yellow, lifting, or unstable flames indicate dirty burners or incorrect gas pressure.
• Inspect grounding: Ensure the burner rack and furnace chassis have a solid ground connection to the control board. Tighten any loose ground screws and remove rust where the ground lug contacts metal.
• Control board check: If the sensor is clean, properly positioned, and the flame is good but E02 persists, the flame sense circuit on the Atlantic main PCB may be defective and require replacement.

Note: If you are not trained to work with gas combustion or cannot verify gas pressure and combustion quality, contact a qualified technician.