Medium
bb on Viessmann Vitodens 200-W B2HA-49

The boiler has lost contact with an add-on part that controls one of the heating zones (the third heating circuit with its mixing valve), so that zone may not heat properly, while the rest of the system should keep working.

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

Communication error, extension kit for heating circuit 3 (with mixer)

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 200 W B2ha 49 60 5817254 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

bAView →bCView →

All 82 fault codes on the Vitodens 200-W B2HA-49

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

4C9A9b9C9E9F1018192028303838:≠0404448505890919293949899A3A4A7b0b1b5b7b8bAbCbdbEbFC1C2C3C4CdCFd6d7d8dAdbdCdddEdFE0E1E2E3E4E5E6E7E8EAEbECEdEEEFF0F1F2F3F6F8F9FAFCFdFEFF

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