1P4 High
Your boiler has detected that the water pressure is too low and needs a top-up to continue working safely.
Technical description: Pressure needs filling to 0.5 – 0.8 bar
Typical repair cost: £0-80 (including labour)
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the valve(s) to allow water into the system while watching the pressure gauge.Close the valves tightly once the pressure reaches between 1.0 and 1.5 bar.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 1P4 — no call-out fees, no surprises.
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Parts commonly replaced
- Filling loop valves
- Pressure sensor
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