BoilerFaultCodesYour boiler has stopped working because the water pressure is too low and needs to be topped up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water pressure too low – the water needs topping up and the vent system or pressure sensor may need replacing
What causes this fault?
This fault occurs when the system loses too much water, preventing the boiler from circulating heat safely. The most common reasons are a slow leak from a radiator valve or the natural loss of pressure that happens after you bleed your radiators. If the pressure looks normal on the gauge but the code persists, the internal sensor that reads the water level may be blocked or broken.
This fault is frequently seen in autumn when homeowners turn their heating back on for the first time, as the change in temperature can highlight small leaks or air pockets in the system.
DIY fix possible
Locate the integrated filling link (blue levers) or the external filling loop underneath the boilerSlowly open the valves until you hear water moving and watch the digital display or pressure gaugeClose the valves firmly once the pressure reaches between 1.0 and 1.5 bar
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 1017 W — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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