BoilerFaultCodesYour heat pump has stopped working because water isn't flowing through the outdoor unit properly, and it has failed to start ten times in a row.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No Water Flow, through Outdoor Unit, 10 times in succession
What causes this fault?
This fault occurs when the system detects that there isn't enough water moving through the outdoor unit to safely transfer heat into your home. The most common reasons are a blockage in the pipework, air trapped in the system, or a circulation pump that has seized up. Because the unit has failed to start ten times, it has locked itself out to prevent the internal components from overheating or freezing.
This issue often appears at the start of autumn when the heating is turned back on after a long summer break, as internal pump parts can become stuck during periods of inactivity.
DIY fix possible
Check that all radiator valves are fully openEnsure the system pressure gauge is between 1.0 and 1.5 barLook for any external valves on the pipework that might be closedClear any debris or blockages from around the outdoor unit fans
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A boiler cover plan would cover faults like E0 — 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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