Communication fault High

Vaillant Communication fault Fault Code

Also written as COMMUNICATIONFAULT — same fault.

The Vaillant Communication fault fault code means: your boiler's internal computer is unable to talk to its display panel, meaning the system has stopped working to protect itself.. It appears on 1 Vaillant 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: No communication with the PCB Communication fault between display and PCB in the electronics box
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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Vaillant models that show the Communication fault fault code

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

Source

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026