Furnace locks out with E2 shortly after ignition, flame appears unstable or goes out

Safety first: Switch off power and close the gas valve before opening the combustion chamber.

• Inspect the burner surface for corrosion, rust flakes, or debris. Clean thoroughly with a soft brush and vacuum.
• Check the ionisation electrode cable for damage, loose spade connectors, or signs of overheating. Reseat or replace as needed.
• Ensure the condensate trap and flue are not partially blocked, as poor combustion air flow can cause flame instability.
• Restore power and gas, reset the unit, and observe operation. If the flame lights but then drops out as the valve modulates, the gas valve or its modulation coil may be faulty and should be tested and replaced by a qualified technician.

Do not attempt to adjust gas valve settings without proper combustion analysis equipment and certification.