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F.104

F.104 — External fault message input active

Viessmann · Vitodens 200-W Boilers

What does F.104 mean?

An external fault message input is active, depending on the configuration of the EM EA1 extension (DIO electronics module). This indicates an issue with a connected external device.

Common Causes

  • Connected external device fault

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Reset the appliance.

  2. 2

    Check the external device connected to the EM EA1 extension (DIO electronics module) for any faults.

  3. 3

    If the fault persists, contact a qualified technician.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

Connection errorConnection error and triangle symbol — Problem with connection to programming unitF.100F.100 — Electronics modules connected to PlusBus not functioning (Voltage error PlusBus)F.142F.142 — Burner in a fault state (Communication error CAN bus)
Source: Viessmann Vitodens 200-W Boilers
Open Manual (Page 64)Search more codes in this manual