Medium
F.671 on Viessmann Vitodens 100-W WB1A

Your boiler has lost the connection to a sensor responsible for tracking stored hot water, likely due to a loose wire or a faulty part.

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

No solar central heating backup, Short circuit, buffer temperature sensor TS3

From this model's manual
Verified against the Viessmann Vitodens 100 W Wb1a installation & service manual, page 99.
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.670View →F.672View →

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