BoilerFaultCodesVokera b 24 Fault Code
Also written as B24 — same fault.
The Vokera b 24 fault code means: your boiler is confused because the water leaving it is cooler than the water returning, suggesting a flow problem or a faulty sensor reading.. It appears on 1 Vokera model in our database.
Technical description: Temperature differential inverted
What causes the Vokera b 24 fault?
This fault occurs when the boiler detects that the return pipe is becoming hotter than the flow pipe, which is the opposite of how the system should function. The most common reasons are a pump failure causing water to circulate backwards, a blockage in the heat exchanger, or one of the temperature sensors sending incorrect data to the control board.
This issue often surfaces when the heating is first turned on after summer, as internal pump components can seize up during long periods of inactivity.
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 →Vokera models that show the b 24 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera b 24 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