BoilerFaultCodesYour boiler has detected that the water pressure in the system is too low, causing it to reduce its output or stop working to prevent damage.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: The current water pressure is too low, limiting the performance in heat mode as well as domestic hot water (DHW) mode
What causes this fault?
This fault occurs when the system loses the physical water pressure required to circulate heat effectively through your radiators. The most common reasons are a slow leak hidden somewhere in your pipework or the pressure naturally dropping after you have recently bled your radiators.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, revealing pressure losses that occurred while the system was idle.
DIY fix possible
Locate the external filling loop, which is usually a silver flexible hose beneath or near the boiler.Open the one or two taps on the filling loop slowly until you hear water entering the system.Monitor the pressure gauge on the boiler front or digital display and close the taps once it reaches 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 H07 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch GB162 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.