BoilerFaultCodesVaillant F11 Fault Code
The Vaillant F11 fault code means: your boiler's main internal computer is having trouble communicating with its electronic components, meaning it cannot process instructions to provide heat.. It appears on 2 Vaillant models in our database.
Technical description: No reception by main board
What causes the Vaillant F11 fault?
This fault occurs when the boiler's main control center loses its electronic link with the rest of the internal components. The most common reason is a hardware failure within the printed circuit board itself or a loose connection in the internal wiring. Without this constant flow of data, the boiler cannot safely coordinate the sequence of ignition or pump activity, causing it to shut down immediately.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Vaillant models that show the F11 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant F11 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