Low
C2 on Viessmann Vitodens 300-W

Your boiler is having trouble talking to the solar heating system, meaning your solar panels may not be contributing to your hot water as they should.

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

Control mode: Communication fault - solar control unit

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 200 W 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.

DIY fix possible

Check if the power switch for the solar control station is turned onInspect the visible connection cable between the boiler and the solar unit for obvious loose plugsReset the boiler to see if the communication link restores itself

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Related fault codes

F4View →

All 60 fault codes on the Vitodens 300-W

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

0F9A9b9C9F101820283038404850515858:05980:092939497:2A2:0A7b0b1b4b5b7b8bAbCbdbEbFC5C6C7CdCECFdAdbdEE4E5E6F0F1F2F3F4F7F8F9FAFdFE

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