Boiler shows E09, burner does not start, and there may be no sound from the gas valve when a call for heat is present.

Safety first: Work on gas valves must only be carried out by qualified personnel. Do not attempt to open or adjust the gas valve without proper training and equipment.

Step-by-step checks (visual only for homeowners):

• 1. Reset boiler: Perform a full reset and observe if E09 returns immediately or only when there is a call for heat.
• 2. Listen for valve click: With a call for heat, listen carefully for a soft click from the gas valve. No click may indicate no power or a failed coil.
• 3. Inspect wiring: With power off, check that the gas valve connector is firmly seated and that the cable is not damaged.

Professional checks: A technician will measure voltage at the gas valve during ignition, test coil resistance, and verify PCB relay operation. If the valve is defective, it must be replaced and gas settings checked with a manometer and flue gas analyser.

When to stop: If E09 persists, do not continue to reset the boiler. Contact an authorised Viadrus service technician.