Low Warning
81:2 on Viessmann Vitodens 050-W

Your boiler is having trouble communicating with its external radio clock module, meaning it may not know the correct time or date for your heating schedule.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

The application of the radioclock module will be recognised automatically

What causes this fault?

This fault occurs when the boiler's main control unit loses its connection to the external radio clock receiver that synchronises the time. The most common reason is a loose wiring connection between the receiver and the boiler, or the internal circuitry of the radio module itself has failed. Because the boiler can no longer confirm the exact time, your programmed heating schedules may become inaccurate.

DIY fix possible

Locate the radio clock module (usually a small white box near the boiler) and ensure it is not blocked by metal objects.Restart the boiler using the power switch to trigger a fresh search for the signal.Access the 'Time and Date' settings via the control panel to manually set the time if the signal cannot be found.

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