Water heater locks out with E02, 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 unstable flame and E02.
• Clean flame sensor: Remove the front cover. Locate the ionisation probe near the burner. Gently clean it with 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 chassis.

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