D.145 Emergency

Vaillant D.145 Fault Code

Also written as D145 — same fault.

The Vaillant D.145 fault code means: your boiler has detected a blockage in the pipes that bring in fresh air or push out exhaust gases, so it has safely shut down to prevent unsafe operation.. It appears on 3 Vaillant models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: Deactivatedetection:Air/fluepipe blocked
Typical repair cost £120-250 (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 D.145 fault code

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

Source

Vaillant D.145 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