How much does it cost to fix Viessmann error code 27?

Typical repair cost for the Viessmann 27 fault is £150-250 including labour.

27 High

Viessmann 27 Fault Code

Q: What does the Viessmann 27 fault code mean?

Your boiler is struggling to detect the flow of water inside it, so it has stopped working to prevent any internal damage.

The Viessmann 27 fault code means: your boiler is struggling to detect the flow of water inside it, so it has stopped working to prevent any internal damage.. It appears on 1 Viessmann model in our database.

Technical description: Differential pressure sensor fault; check flow. Interruption or short circuit

Typical repair cost £150-250 (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 27 fault code

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

Vitodens Repair: £150-250

Source

Viessmann 27 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