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BF

Fault BF — Incorrect LON communication module

Viessmann · Vitodens 200-W B2HB Boiler

What does BF mean?

The boiler is in control mode but detects an issue with the LON communication module, indicating it is incorrect or faulty. This module is essential for proper communication within the system.

Common Causes

  • Incorrect LON communication module installed
  • Faulty LON communication module

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off the boiler at the main power switch and wait a few minutes before turning it back on.

  2. 2

    Verify that the correct LON communication module is installed.

  3. 3

    If the module is confirmed correct, it may be faulty and require replacement.

  4. 4

    Contact a qualified service technician to diagnose and replace the LON communication module.

Browse all codes in this manual (56)
Verified technical data. Last updated: April 2026

Related Faults

0F0F — Boiler requires service1010 — Short circuit on outdoor temperature sensor1818 — Outdoor temperature sensor cable broken
Source: Viessmann Vitodens 200-W B2HB Boiler
Open Manual (Page 78)Search more codes in this manual