BoilerFaultCodesVaillant F14 Fault Code
The Vaillant F14 fault code means: your boiler has shut down because it has detected that the water inside is getting much too hot, which is usually caused by a circulation problem.. It appears on 2 Vaillant models in our database.
Technical description: Central heating flow t° > 95° C
What causes the Vaillant F14 fault?
This fault occurs when the water inside the boiler heats up too quickly or reaches an unsafe temperature, forcing the system to shut down for safety. The most common reason is a pump failure or a blockage that prevents water from moving through the pipes, causing the heat to build up in one spot rather than being distributed to your radiators.
This fault is frequently seen at the start of autumn when heating systems are turned on for the first time after summer, as pump components can seize during long periods of inactivity.
DIY fix possible
Check that your radiator valves are fully open to allow water to flow.Ensure your system pressure is topped up to between 1 and 1.5 bar on the gauge.Try resetting the boiler to see if the error clears once the water cools down.
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Gas Safe Register →Vaillant models that show the F14 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant F14 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