Boiler locks out with E02, burner stops shortly after ignition or during operation.

Safety: Switch off power and close the gas valve before opening the boiler casing. Allow the unit to cool.

Steps:

• Check gas supply stability: Confirm that other gas appliances run without interruption. If they also cut out, contact your gas supplier.
• Inspect burner and heat exchanger: Remove the burner cover on the Attack boiler. Look for heavy soot, rust flakes, or debris on the burner surface. Clean gently with a soft brush and vacuum. Do not deform burner ports.
• Clean flame sensor: Remove the flame ionization electrode and clean the tip with fine abrasive pad. Reinstall ensuring correct immersion into the flame as per Attack service instructions.
• Check condensate drain: On Attack condensing boilers, a blocked condensate trap can cause poor combustion and flame loss. Remove and flush the condensate trap and check the drain hose for kinks or blockage.
• Inspect wiring to PCB: Ensure the electrode cable and gas valve connector are firmly attached to the main control PCB and show no signs of burning or corrosion.

Call a professional: If E02 recurs, a technician should measure gas pressure, check combustion with an analyzer, and test the main PCB.