Boiler displays error code 02 and locks out shortly after an ignition attempt; the flame appears briefly then extinguishes.

Safety warning: Work on gas and combustion components must be carried out by a qualified technician. Isolate power and gas before opening the boiler casing.

• Check gas supply stability: Confirm that other gas appliances do not fluctuate or extinguish. If they do, contact the gas supplier.
• Inspect burner: Remove the burner assembly as per Immergas service instructions. Check for rust, debris, or soot blocking the burner ports. Clean with a soft brush and vacuum; do not enlarge the ports.
• Check ionisation electrode: Ensure the electrode is correctly positioned in the flame, clean, and free from cracks. Verify that the cable is not damaged and is firmly connected to the PCB.
• Verify gas valve modulation (engineer only): Using a manometer, check that the gas valve maintains the correct burner pressure during operation. If pressure drops or the valve cuts out, replace the gas valve.
• Check flue and air intake: Ensure the flue terminal is not blocked by leaves, ice, or debris, and that the concentric flue is correctly fitted. Poor combustion air can cause flame instability.
• Test operation: After reassembly, operate the boiler at maximum and minimum power to ensure the flame remains stable and error 02 does not recur.