Boiler locks out with A02, burner shuts down shortly after ignition, repeated failed starts

Safety: Switch the boiler off and allow it to cool. If you smell gas, close the gas valve and ventilate the area, then call a professional.

User checks:

• Gas supply stability: Confirm other gas appliances run without cutting out. If they also fail, contact your gas supplier.
• Ventilation and flue: Ensure air inlets and the concentric flue terminal are not blocked by debris, snow, or objects.
• Reset: Perform a single reset via the control panel. If the boiler lights and then cuts out again with A02, do not keep resetting.

Technician actions:

• Check and adjust gas valve pressure settings according to Fondital specifications.
• Remove and clean the main burner and combustion chamber, removing dust, rust flakes, or soot.
• Inspect and test the flame detection electrode and its cable; replace if worn or cracked.
• Verify correct operation of the Fondital main PCB flame supervision circuit and replace the PCB if no other cause is found.