BoilerFaultCodesVaillant F13 Fault Code
The Vaillant F13 fault code means: your boiler's computer brain has encountered a serious communication error and can no longer control the heating system safely.. It appears on 2 Vaillant models in our database.
Technical description: Main board fault
What causes the Vaillant F13 fault?
This fault occurs when the boiler's internal computer experiences a major electrical short or a critical component failure on the control board. The most common reason is general wear and tear of the electrical circuits over time, or pulse damage caused by a power surge.
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 F13 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant F13 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