Furnace stops and displays E06, often after several failed ignition attempts or erratic operation.

Safety: Turn off power at the breaker before touching any wiring.

Steps:

• Power cycle: Turn off the furnace breaker for 5 minutes, then restore power. This can clear transient faults on some Atlantic electronic boards.
• Inspect wiring harnesses: Remove the control compartment cover and check all plug-in connectors to the Atlantic main PCB (thermostat, gas valve, inducer, blower, sensors). Reseat each connector firmly.
• Check for moisture or corrosion: Look for signs of water leaks, condensation, or corrosion on the board and connectors. Address any source of moisture (e.g., leaking humidifier, flue condensation).
• Verify correct supply voltage: Ensure the furnace is receiving the rated line voltage (typically 230 V or 120 V depending on region) and that neutral/ground connections are tight. This test should be done by a qualified person.

Note: If E06 returns after checks, the Atlantic control board is likely defective and should be replaced with the exact part number specified for your model.