P.11 Low

Vaillant P.11 Fault Code

Also written as P11 — same fault.

The Vaillant P.11 fault code means: your boiler is currently running a setup program to test its gas pressure and is not in its normal operating mode.. It appears on 1 Vaillant model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Setting-up program: Natural Gas (G20) mid setting point pressure

DIY fix possible

Wait for the program to finish automaticallyPress the 'i' button to monitor progressIf it persists, turn the boiler off and on again to reset it

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Vaillant models that show the P.11 fault code

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

Source

Vaillant P.11 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