BoilerFaultCodesVokera b19 Fault Code
Also written as B19 — same fault.
The Vokera b19 fault code means: your boiler has detected that the water returning to the unit is much too hot, suggesting it isn't circulating properly through your radiators or pipes.. It appears on 1 Vokera model in our database.
Technical description: Return sensor above 95 °C
What causes the Vokera b19 fault?
This fault occurs when water cannot move away from the boiler quickly enough, causing the temperature at the return pipe to spike dangerously high. The most common reasons are a seized internal pump failing to push the water or a major blockage in the pipework or heat exchanger that is strangling the flow. It can also be caused by a faulty sensor sending an incorrect high-temperature reading to the control board.
This fault often appears during the first cold spell of autumn when heating systems are turned back on after months of inactivity, which can cause internal pump components to seize.
DIY fix possible
Check that all radiator valves are fully openEnsure the boiler pressure is between 1.0 and 1.5 barCheck if any bypass valves are closed or if there is a blockage in the system
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Gas Safe Register →Vokera models that show the b19 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera b19 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