BoilerFaultCodesYour boiler has stopped working because it cannot correctly detect the water pressure, often due to a low water level or a faulty sensor.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water filling error – check water pressure sensor
What causes this 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
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E23 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Keston C36 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.