Water heater locks out with error 02; burner lights briefly then shuts down.

Safety: Isolate power and gas before opening the casing. Allow the appliance to cool.

Steps:

• Check flue and air intake: Ensure the flue terminal is not blocked by leaves, snow, or debris. Confirm the air intake is clear and that the flue is properly assembled and sealed.
• Inspect burner and heat exchanger: Remove the burner cover. Look for soot, rust, or scale on the burner and primary heat exchanger. Clean gently with a soft brush and vacuum. Excessive soot indicates combustion issues that require a technician.
• Clean flame sensor: Remove the ionisation probe and clean the metal rod with fine abrasive pad. Refit securely and ensure correct positioning in the flame.
• Check gas supply stability: If other gas appliances fluctuate or go out, there may be a supply or regulator issue. Do not attempt to adjust gas pressure yourself; contact a licensed gas engineer.

Note: Persistent error 02 after cleaning and basic checks usually indicates a failing gas valve or control board and should be handled by a qualified Biasi technician.