Ferroli furnace locks out with A02, fan runs but burner shuts down shortly after ignition attempt.

Safety: Isolate power and gas before opening the combustion chamber. Only qualified personnel should work on sealed combustion components.

Steps:

• Visual inspection: Remove the front panel and check for loose earth (ground) wires on the burner, gas valve, and control board chassis. Tighten any loose screws.
• Clean flame sensor: Remove the ionisation electrode and gently clean the metal rod with fine abrasive pad. Avoid bending the rod. Reinstall ensuring correct gap and position in the flame.
• Check burner condition: Inspect for corrosion, soot, or partial blockage that could cause unstable flame. Clean with a soft brush and vacuum.
• Check condensate trap (if condensing model): A blocked Ferroli condensate trap can disturb combustion. Remove the trap, flush with water, and ensure the drain line is clear.
• Monitor operation: Restore power and gas, reset the unit, and observe ignition. If the flame lights but drops out, gas pressure or control board may be at fault.

Professional help: A licensed technician should measure gas inlet and burner pressure, verify correct combustion with an analyser, and replace the control board or gas valve if the flame signal remains unstable.