F.342 High

Vaillant F.342 Fault Code

Also written as F342 — same fault.

The Vaillant F.342 fault code means: your boiler is struggling to push the right amount of air through its system to burn gas safely, so it has stopped working to prevent any potential danger.. It appears on 4 Vaillant models 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: Fan speed does not correspond to the target value. The air-mass flow is not within the permitted limits.
Typical repair cost £180-350 (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 F.342 fault code

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

Source

Vaillant F.342 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 31 August 2026