Medium
F.545 on Viessmann Vitodens 222-F B2TF

A sensor that monitors the temperature for your second heating zone (such as underfloor heating) has developed an electrical fault, causing your boiler to close the mixing valve to prevent overheating.

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.

What the manual says

Manufacturer manual

Mixer closes. Heating circuit pump is operational. Short circuit, flow temperature sensor, heating circuit 2 with mixer.

From this model's manual
Verified against the Viessmann Vitodens 222 F B2tf installation & service manual, page 105.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

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

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Related fault codes

F.544View →F.546View →

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