Vaillant · ecoTEC plus Boilers
If the display language has been unintentionally set to a language you cannot understand during the installation assistant or initial setup, there is a specific button sequence to reset it.
Click steps to track your progress.
Press and hold both the 'minus' (left arrow) button and the 'OK' (checkmark) button simultaneously.
While continuing to hold these two buttons, briefly press the 'on/off' button.
Keep holding the 'minus' and 'OK' buttons until the language setting option visibly appears on the display screen.
Select your desired language from the list using the navigation buttons.
Press the 'OK' (checkmark) button twice to confirm your selection and save the new language.