Medium
40 on Viessmann Vitodens 100-W WB1A

Your boiler is receiving an incorrect electrical signal from a temperature sensor, which is preventing it from accurately monitoring the warmth of your home's heating supply.

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

Heating circuit M2 flow temperature sensor shorted out

From this model's manual
Verified against the Viessmann Vitodens 100 W Wb1a installation & service manual.
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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