E6 displayed, burner shuts down shortly after ignition

Safety first: Turn gas OFF and disconnect power. Do not operate the heater if you suspect a venting or gas supply problem. Risk of carbon monoxide and explosion.

• Check gas supply: Ensure the manual gas shutoff valve to the Giant heater is fully open. If other gas appliances are also weak, contact your gas supplier.
• Inspect burner and orifice: Remove the burner assembly and check for debris, rust, or spider webs in the burner ports and orifice. Clean with a soft brush and compressed air. Do not enlarge the orifice.
• Verify venting: Inspect the vent pipe for obstructions, sagging, or disconnections. For power‑vent Giant models, ensure the blower and intake/exhaust pipes are clear.
• Reassemble and test: Reinstall burner and covers, restore gas and power, and test. If E6 persists, the gas control valve or control board may be defective and should be evaluated by a licensed technician.