00:4 Low

Viessmann 00:4 Fault Code

Also written as 004 — same fault.

The Viessmann 00:4 fault code means: your boiler's internal settings are currently configured to manage your home heating zones and hot water separately, which is a normal state for this model rather than a sign of a mechanical failure.. It appears on 6 Viessmann models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: System design 2, 5: 1 mixer circuit M2, with DHW heating

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 00:4 fault code

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

Source

Viessmann 00:4 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 27 April 2026