Electronic gas water heater will not ignite; display shows E01 and burner never lights.

Safety first: Turn the gas control knob to OFF, shut off the manual gas shutoff valve, and disconnect power before working on the heater. Allow the unit to cool completely.

• 1. Power reset: Restore power, then turn the gas control to ON and attempt a reset per the user manual (often by pressing and holding the reset or temperature button). If E01 returns, continue.
• 2. Inspect flame sensor: Remove the burner access cover. Locate the flame sensor rod near the burner. Gently clean it with fine steel wool or a Scotch-Brite pad to remove oxidation. Do not bend the rod. Reinstall and reconnect the wire firmly.
• 3. Check igniter: For spark igniter models, observe through the sight glass while calling for hot water. Look for a strong blue spark at the burner. For hot surface igniter models, look for a bright orange glow. If there is no spark or glow, the igniter assembly may be faulty.
• 4. Inspect burner and orifice: Remove the burner assembly. Check the main burner and orifice for spider webs, dust, or debris. Clean with compressed air and a soft brush. Do not enlarge the orifice.
• 5. Verify gas supply: Ensure the manual gas shutoff valve is fully open. If other gas appliances are weak or not working, contact your gas supplier. Do not attempt to adjust internal gas pressure yourself.
• 6. Reassemble and test: Reinstall the burner assembly, ensuring the gasket is seated and screws are tight. Restore gas and power, then test operation. If E01 persists, the gas control valve or ignition module may need replacement by a qualified technician.