Furnace starts, inducer runs, but burners do not light; E03 code appears after several attempts.

Safety: Turn off power and shut off gas before touching the gas train. Do not attempt gas pressure adjustments without proper tools and training.

• Check manual gas shutoff: Verify the gas cock near the furnace is parallel to the pipe (open). If perpendicular, turn it to open position.
• Inspect wiring to gas valve: Remove the burner compartment door. Locate the Alpha gas valve on the gas manifold. Confirm the 2–3 wire connector is firmly attached and wires are not damaged.
• Listen for valve click: Restore power and gas, then call for heat. After the inducer starts and the igniter glows, listen for a distinct click from the gas valve. No click suggests the valve is not being energized or is defective.
• Do not bypass safety circuits: Never jump or manually power the gas valve. If the valve is not opening and wiring is intact, the gas valve or control board must be tested and replaced by a qualified technician.

If you smell gas or hear hissing without ignition, shut off gas immediately and contact a professional.