Low
28 on Viessmann Vitodens 343-F WS4A

The boiler has lost its reading of how hot the water leaving it is, so it is using a backup method to control the heating, which usually keeps things working but should be checked by an engineer soon.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Regulates without flow temperature sensor (low loss header). Cause: System flow temperature sensor lead broken.

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 343 F Ws4a 5592883 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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Related fault codes

27View →29View →

All 59 fault codes on the Vitodens 343-F WS4A

Seeing a different code? Every code this model can display, in one place.

0F9A9b9C9F101820303840485058929394A6A7b0b1b4b5b7b8bAbCbdbEbFC2CdCECFdAdbdddEE4E5E8E9EAEbECEdF0F1F2F3F4F8F9FAFCFdFEFF

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