BoilerFaultCodesYour boiler has detected that the water pressure is too low, which prevents the system from running safely and efficiently.
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 in CH system low
What causes this fault?
This fault occurs when there is not enough water in your heating system to maintain the required pressure for operation. The most common reason is a slow leak from a radiator valve or pipework, though it can also happen if air was recently bled from your radiators without the system being topped back up.
This issue is more frequent in autumn when homeowners turn their heating back on for the first time and discover that pressure has dropped over the summer months.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath or near the boilerSlowly open the one or two valves on the hose until you hear water movingWatch the display until the pressure reaches between 1.0 and 1.5 bar, then close the valves tightly
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 P0.5-0.9 bar — no call-out fees, no surprises.
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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.
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