Medium
102 on Viessmann Vitodens 100-W B1HF-11

Your boiler's control system has lost reliable contact with one of its communication parts, so it may not respond properly to your thermostat or app, but this is not a gas safety issue.

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

Error with communication module

From this model's manual
Verified against the Viessmann/Viessmann Vitodens 100 W B1hf B1kf 6167586 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

Switch the boiler off at its on/off switch and at the household isolator or fuse for at least 60 seconds, then switch it back on to reset the control system.Check that your room thermostat, Vitotrol or internet gateway (if fitted) has fresh batteries or power, and that any wireless link shows as connected.If the code returns, leave the boiler off and contact a Gas Safe registered engineer to check the communication module and its wiring.

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Related fault codes

All 151 fault codes on the Vitodens 100-W B1HF-11

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

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