Boiler displays error 02 and shuts down shortly after starting, burner stops unexpectedly.

Safety: Isolate electrical power and close the gas valve before removing the boiler case. Gas and combustion checks must be done by a qualified engineer.

• Check for pattern: Note if the boiler runs for a few seconds or minutes before 02 appears. This helps identify if the issue is combustion stability or control-related.
• Verify flue and air intake: Ensure the Biasi concentric flue terminal is not blocked by debris, snow, or vegetation. A restricted flue can cause poor combustion and flame loss.
• Inspect burner and electrodes: With the combustion chamber open, check the burner surface for corrosion or debris. Clean as per Biasi instructions. Clean and inspect the flame electrode and its cable.
• Check system gas supply: Confirm other gas appliances operate normally. If they also cut out, contact the gas supplier.
• Engineer checks: A technician should measure gas inlet pressure, burner pressure, and combustion (CO/CO₂) to ensure the gas valve and burner are correctly set. They should also verify the flame signal at the PCB.
• Do not bypass safety devices: Never attempt to bridge or bypass flame sensing or gas valve controls.