N.319 Medium

Vaillant N.319 Fault Code

Also written as N319 — same fault.

The Vaillant N.319 fault code means: your boiler is struggling to circulate water effectively because an internal safety valve is stuck or blocked, which may cause it to turn itself off to prevent overheating.. It appears on 3 Vaillant models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: The unit's internal bypass valve is blocked.
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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Vaillant models that show the N.319 fault code

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

Source

Vaillant N.319 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 7 July 2026