BoilerFaultCodesYour heat pump has detected that the internal pressure is too high and has shut down to protect its internal components.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: High Pressure Switch Operated
What causes this fault?
This fault occurs when the refrigerant pressure inside the heat pump exceeds safe working limits, causing the system to shut down to prevent damage. The most common reasons are a lack of water flow through the unit, often caused by a blocked filter, or a pump failing to move heat away from the system quickly enough.
This fault is more frequent during the first cold snaps of autumn or winter when the heat pump is required to work at its maximum capacity for the first time in months.
DIY fix possible
Ensure all radiator valves and zone valves are fully open to allow water to flow.Check that your external heating filters (like a magnetic filter) are not blocked with debris.Restart the unit to see if the fault clears after checking the water flow.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like P1 — 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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