BoilerFaultCodesYour boiler has detected that there is not enough water pressure in the central heating system to operate safely.
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 in CH system low. Replenish CH system & purge air. Find leak(s) and repair. Compare analogue gauge pressure.
What causes this fault?
This fault occurs when the water inside your radiators and pipework has dropped below the minimum level required for the boiler to fire up safely. The most common reasons are a slow leak somewhere in the system, air being released through valves, or the internal expansion vessel losing its air charge over time.
This issue is frequently seen in autumn when the heating is turned on for the first time after summer, as dormant leaks or air pockets often become apparent once the system is pressurised and heated.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Open the small valves on the filling loop slowly to let water into the system.Watch the pressure gauge and close the valves once the pressure 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 P0.5-0.9 — no call-out fees, no surprises.
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Potterton Powermax HE 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.
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