BoilerFaultCodesKeston E23 Fault Code
The Keston E23 fault code means: your boiler has stopped working because it cannot correctly detect the water pressure, often due to a low water level or a faulty sensor.. It appears on 9 Keston models in our database.
Technical description: Water filling error - check water pressure sensor.
What causes the Keston E23 fault?
This fault occurs when the boiler's internal computer is unable to detect a stable reading from the water pressure sensor, which is essential for safe operation. The most common reason is that the system water level has dropped too low, but it can also be triggered if the sensor itself has become blocked with debris or has failed electronically.
This fault is more common in autumn when homeowners turn their heating back on for the first time, as small leaks over the summer may have caused the system pressure to drop.
DIY fix possible
Check the pressure gauge on the front of the boilerIf the pressure is below 1 bar, use the filling loop to top it up to 1.5 barReset the boiler by pressing the 'Reset' button
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Gas Safe Register →Keston models that show the E23 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston E23 fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026