Low
F.673 on Viessmann Vitodens 200-W B2KE-25

Your boiler has noticed a fault in the sensor that monitors the solar water heating panels on your roof, so the solar part of your hot water system may not be working properly, though your main heating and hot water should still be running.

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

Thermostat function for solar control and solar transfer pump not working - Short circuit, temperature sensor, thermostat function TS3

From this model's manual
Verified against the Viessmann/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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Related fault codes

F.672View →F.674View →

All 170 fault codes on the Vitodens 200-W B2KE-25

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

F.7F.8F.9F.10F.11F.12F.13F.14F.15F.16F.29F.30F.49F.50F.57F.58F.59F.62F.63F.65F.67F.68F.69F.70F.71F.72F.73F.74F.77F.89F.91F.92F.93F.94F.100F.104F.142F.160F.161F.162F.163F.182F.183F.184F.185F.299F.342F.345F.346F.348F.349F.350F.351F.352F.353F.354F.355F.357F.359F.361F.365F.366F.367F.368F.369F.370F.372F.373F.375F.377F.378F.380F.381F.382F.383F.384F.385F.386F.387F.388F.395F.396F.399F.400F.401F.402F.403F.404F.405F.406F.408F.410F.416F.417F.418F.425F.426F.427F.428F.429F.430F.432F.433F.436F.437F.440F.441F.442F.443F.444F.445F.446F.447F.448F.449F.450F.451F.452F.453F.454F.455F.456F.457F.458F.461F.462F.463F.464F.467F.468F.471F.473F.474F.517F.527F.528F.530F.538F.539F.540F.542F.543F.544F.545F.546F.547F.574F.575F.576F.577F.578F.579F.580F.581F.582F.666F.667F.668F.669F.670F.671F.672F.682F.683F.684I.55I.56I.57I.59

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