Your boiler has lost power or has a serious internal electronic failure, meaning it cannot start the ignition process to provide heating or hot water.

No green light (Red lights function)

What causes this fault?

This fault occurs when the boiler's control system loses its vital electrical feed, preventing it from managing the heating process. The most common reason is a blown internal fuse or a failure within the Printed Circuit Board (PCB) which acts as the boiler's brain. In some cases, a faulty transformer is unable to convert power correctly, leading to a total loss of the green operation light.