BoilerFaultCodesVokera E040 Fault Code
The Vokera E040 fault code means: your boiler has detected that the water pressure is either too low or the sensor that monitors it is not communicating correctly.. It appears on 4 Vokera models in our database.
Technical description: Water transducer – check system water pressure
What causes the Vokera E040 fault?
This fault occurs when the boiler's internal sensor detects that there isn't enough water pressure to safely heat your home, or if the sensor itself has developed an electrical fault. The most common reason is a gradual loss of water through a small leak or from bleeding your radiators, which drops the pressure below the required operational limit. When this happens, the boiler shuts down as a safety precaution to prevent the internal components from overheating.
This fault is slightly more common in autumn when homeowners turn their heating back on after the summer, as the change in temperature can highlight pressure drops or minor leaks that developed while the system was idle.
DIY fix possible
Locate the pressure gauge on the front of the boiler or via the digital screen.If the pressure is below 1 bar, use the filling loop underneath the boiler to carefully top it up to 1.5 bar.Restart the boiler to see if the error clears once the pressure is stable.
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Gas Safe Register →Vokera models that show the E040 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera E040 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