Electronic GSW gas water heater will not ignite; display shows E001 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.

• Check gas supply: Verify the gas shutoff valve to the GSW heater is fully open. Confirm other gas appliances in the home are working to rule out a supply issue.
• Inspect the igniter: Remove the burner access cover. Locate the hot surface igniter or spark igniter near the main burner. Look for cracks, heavy white deposits, or broken wiring. If damaged, replace the igniter assembly with a GSW-compatible igniter.
• Clean the flame sensor: The flame rod is usually next to the burner. Gently clean it with fine emery cloth or a Scotch-Brite pad to remove oxidation. Do not bend or scratch it deeply. Reinstall securely.
• Check wiring connections: Inspect the harness from the control board to the igniter and flame sensor. Reseat any loose connectors and look for burnt or pinched wires.
• Reset the control: Restore power and gas, then follow the GSW lighting instructions. If E001 returns after several attempts, the gas control valve or control board may be defective and should be tested or replaced by a qualified technician.