Your boiler is struggling to deliver the correct mix of air and gas required to light the burner safely.

Opening air/gas ratio control valve/oil solenoid valves

What causes this fault?

This fault occurs when the boiler's internal computer is unable to communicate with or control the valve that regulates the flow of gas into the burner. It signifies a hardware failure where the gas valve remains closed or unresponsive, preventing the boiler from creating a flame to provide heating or hot water. The most common reasons include a faulty electronic control board, a loose wiring connection, or a mechanical failure within the gas valve itself.