Vaillant smart thermostat shows 'Service due' or similar maintenance reminder and user is unsure how to clear it.

Safety: Do not ignore service reminders; they relate to boiler safety and efficiency.

• 1. Arrange service: Book a boiler and system service with a Vaillant‑approved engineer.
• 2. Engineer reset: After completing maintenance, the engineer can reset the service interval via the installer menu on the thermostat or boiler.
• 3. User reset (if allowed): Some models allow the user to acknowledge the reminder in the menu, but this should only be done after actual servicing.
• 4. Do not bypass permanently: Avoid disabling service reminders entirely; they are important for long‑term safety.