Medium Warning
A7 on Viessmann Vitodens 333

Your boiler's control panel and the main internal computer are having trouble talking to each other, meaning the display might not work correctly or respond to your settings.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Control mode - Faulty operating interface

What causes this fault?

This fault occurs when the data link between the boiler's front display panel and the internal main circuit board is interrupted or corrupted. It is usually caused by a loose internal connection cable, moisture ingress affecting the buttons, or a component failure within the digital interface itself.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

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