BoilerFaultCodesVokera b/E 18 Fault Code
Also written as BE18 — same fault.
The Vokera b/E 18 fault code means: your boiler is unable to move water around the system because the pump is stuck or a valve has been accidentally closed.. It appears on 2 Vokera models in our database.
Technical description: Pump seized / Flow/return service valve closed
What causes the Vokera b/E 18 fault?
This fault occurs when the boiler detects that water isn't moving through the heat exchanger, often because the internal pump has physically seized after a period of inactivity. It can also be triggered if the service valves underneath the boiler have been accidentally turned off during DIY or maintenance, or if a build-up of sludge is blocking the internal flow. Without this circulation, the boiler shuts down to prevent the unit from overheating.
This issue is particularly common in autumn when homeowners turn their heating on for the first time after the summer, as the pump can stick if it hasn't moved for several months.
DIY fix possible
Check that the isolation valves underneath the boiler are in the open position (parallel to the pipework).Ensure all radiator valves are open to allow water to circulate.Try resetting the boiler to see if the pump clears its own blockage.
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Gas Safe Register →Vokera models that show the b/E 18 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera b/E 18 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