Vaillant Boiler PCB Failure: Why Your Boiler Screen Turns On Then Off AgainIf you own a Vaillant boiler and notice the screen lights up for a few seconds when the power is switched on, only to go off again, the problem could be a PCB (Printed Circuit Board) failure.The PCB is the “brain” of your boiler, controlling key components such as the pump, fan, and safety sensors. When it fails, your boiler will struggle to power up properly—or not work at all.In this guide, we’ll cover: What a PCB is...