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

Safety: Switch off power and close the gas valve before removing covers.

• Check gas pressure stability: If other gas appliances flicker or go out, contact your gas supplier. Do not attempt to adjust the main gas regulator yourself.
• Clean burner: Remove the burner assembly from the Klimosz boiler. Brush off soot and corrosion from the burner surface and ports. Use compressed air to blow through the burner holes.
• Inspect flame sensor: Clean the ionization electrode with fine abrasive pad. Ensure correct positioning in the flame path as per Klimosz service manual (typically a few millimeters above burner surface).
• Check gas valve connections: Verify that the gas valve coil connectors are firmly seated and not corroded. Look for signs of overheating or burning on the valve body.
• Restart and monitor: Restore gas and power, reset the boiler, and observe operation. If the flame still drops out and E02 returns, the gas valve or control board may need professional diagnosis and replacement.