BoilerFaultCodesVokera 23 Fault Code
The Vokera 23 fault code means: your boiler has built up too much internal water pressure and is releasing it through a safety valve to prevent damage.. It appears on 4 Vokera models in our database.
Technical description: Safety valve is prompted to relieve excess pressure from the primary circuit
What causes the Vokera 23 fault?
This fault occurs when the water pressure inside your heating system rises above safe levels, often because the expansion vessel has lost its air charge or failed. The boiler triggers this code as it uses a safety valve to eject water and protect internal components from being crushed by the high pressure. It can also happen if the filling loop was left slightly open, causing the system to overfill unintentionally.
This fault is more common in winter when homeowners turn their heating on for the first time, as the rapid heating of water puts the most strain on the expansion vessel.
DIY fix possible
Check that the filling loop valves are fully closed and not letting in more waterBleed water from a radiator to reduce the system pressure to between 1.0 and 1.5 barCheck the external copper discharge pipe for signs of drippingIf the pressure continues to rise or the valve leaks, call a Gas Safe engineer
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Vokera models that show the 23 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera 23 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026