F.764 High

Viessmann F.764 Fault Code

Also written as F764 — same fault.

The Viessmann F.764 fault code means: your boiler is connected to another unit that is reporting a problem, which is preventing your system from working correctly.. It appears on 1 Viessmann model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: System in a fault state. Lag appliance reports a fault.
Typical repair cost £150-350 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Viessmann models that show the F.764 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Viessmann F.764 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026