Medium Service
63:2 to 63:14 on Viessmann Vitodens 300-W

Your boiler is experiencing a communication error with the internal control system that is intermittently disrupting your heating and hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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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

Every 2 to every 14 days

What causes this fault?

This notification is triggered by the boiler's internal timer reaching a pre-set date or number of burner operating hours. It serves as an automated reminder that the manufacturer's recommended maintenance window has arrived to ensure continued efficiency. It is not caused by a mechanical failure, but rather by the system tracking its own usage history.

Engineer required

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

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Related fault codes

63:1View →F1View →F2View →

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