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F.425

F.425 — Time synchronization failed, normal operation with calculation error

Viessmann · Vitodens 100-W Boiler

What does F.425 mean?

The system is operating normally, but a calculation function is not working because time synchronization failed. This may affect scheduling or data logging.

Common Causes

  • Time synchronization failed

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the current time displayed on the boiler and set it correctly.

  2. 2

    If external time is used, verify the settings for parameters 1504 and 508.

  3. 3

    Reset the boiler after adjusting time settings to allow it to resynchronize.

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
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