BoilerFaultCodesYour boiler has detected that the water pressure is too low for it to run safely, or there is a blockage preventing water from circulating.
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 or no water flow
What causes this fault?
This fault occurs when the boiler detects that there isn't enough water pressure in the system to operate safely, or the water isn't moving through the unit correctly. The most common reason is a gradual loss of pressure through small leaks or after bleeding your radiators, but it can also be triggered by a faulty pump that isn't pushing water around the circuit.
This issue often appears when you first turn the heating back on for autumn, as the system has been dormant and may have lost pressure over the summer months.
DIY fix possible
Check the pressure gauge on your boiler or under the sink; it should be between 1.0 and 1.5 bar.Locate the filling loop (a flexible silver hose) and slowly open the valves until the pressure reaches 1.2 bar.Ensure all radiator valves are open and your external pump (if applicable) is running.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like E04 — 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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