Vaillant · ecoTEC plus Boilers
This fault indicates an issue with the gas valve, which controls the flow of gas to the burner. It might not be connected correctly or could have an internal fault.
Click steps to track your progress.
Press and hold the reset button for more than three seconds to try and clear the fault.
Do not attempt to inspect or adjust the gas valve yourself due to safety risks.
Contact customer service immediately. A qualified technician will need to check the gas valve and its connections.