Electronic John Wood gas water heater displays E003 and shuts down shortly after burner lights

Safety: Turn off gas and power before opening any access panels. Allow the burner area to cool.

• 1. Clean flame sensor: Remove the burner assembly following the service manual. Gently clean the flame sensor rod with fine abrasive pad until bright metal is visible. Reinstall securely.
• 2. Check ground connections: Verify that the burner assembly and gas valve have solid metal-to-metal contact with the tank and that any ground wires are tight and free of corrosion.
• 3. Inspect burner flame: With panels reinstalled, restore gas and power and observe the flame through the sight glass. The flame should be steady and mostly blue. Yellow, lifting, or noisy flames can indicate low gas pressure or burner contamination.
• 4. Gas supply check: Ensure the manual gas valve is fully open. If other gas appliances show issues, contact your gas supplier to check pressure.
• 5. Replace gas control if needed: If the flame is stable and the sensor is clean but E003 persists, the gas control valve/thermostat module may not be reading the flame signal correctly and should be replaced as a complete assembly.

Warning: Do not attempt to adjust internal gas valve components. Only replace as a unit.