Water heater locks out with E02; the burner shuts down shortly after ignition or during operation.

Safety: Isolate power and gas before opening the appliance. Flame detection issues involve combustion; improper repair can be dangerous.

Steps:

• Check for drafts or flue issues: Ensure the flue terminal is not exposed to strong wind or blocked. A partially blocked concentric flue on Baxi heaters can cause an unstable flame and E02.
• Clean flame sensor: Remove the front cover. Locate the ionization probe near the burner. Gently clean it with a fine abrasive pad to remove oxidation. Ensure the probe is firmly mounted and in the flame path.
• Inspect burner: Check the Baxi burner for heavy soot or debris. Vacuum gently and avoid damaging the burner mesh or ports.
• Check wiring: Confirm the flame sensor lead is firmly connected to the control PCB and not damaged or shorted to the chassis.

Professional checks: If the problem persists, a technician should measure ionization current, verify gas inlet and burner pressure, and test/replace the Baxi control PCB or gas valve if required.