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F.385

F.385 — Burner in fault state: Short circuit in ionization current signal

Viessmann · Vitodens 100-W Boiler

What does F.385 mean?

The burner is in a fault state due to a short circuit in the ionization current signal. This can also indicate a problem with the BCU burner control unit.

Common Causes

  • Short circuit in ionization current signal
  • Faulty ionization electrode or connecting cable
  • Faulty BCU burner control unit

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the ionization electrode and its connecting cable for any signs of damage or short circuits.

  2. 2

    Ensure the connecting cable is firmly seated and free from moisture.

  3. 3

    Reset the boiler by briefly turning off and on its power supply. If the fault persists, contact a qualified heating engineer.

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

Related Faults

Connection errorConnection error — Displayed on programming unitF.142F.142 — Burner in fault state due to CAN bus communication errorF.160F.160 — Burner in fault state due to CAN bus communication error
Source: Viessmann Vitodens 100-W Boiler
Open Manual (Page 78)Search more codes in this manual