High
0C on Viessmann Vitodens

Your boiler is struggling to switch between heating your radiators and heating your hot water because a internal physical valve is getting stuck.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Three-way mixer

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

0BView →0DView →

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