Medium
C3 on Viessmann Vitodens 200-W WB2C 19kW System

The boiler's add-on control unit has lost its connection to the main boiler, so it may stop working properly until the link is restored, but this is usually a fixable wiring or part issue.

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

Extension AM1 communication error

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 200 W Wb2c Service 5692857 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

C4View →F0View →

All 82 fault codes on the Vitodens 200-W WB2C 19kW System

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

4C9A9b9C9E9F1018202830384044485051585990919293949899A7b0b1b5b7b8bAbbbCbdbEbFC1C2C4C5C6C7C8CdCECFd6d7d8dAdbdCdddEdFE0E1E3E4E5E7E8EAEbECEdEEEFF0F1F2F3F8F9FAFCFdFEFF

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