BoilerFaultCodesWhat the manual says
Manufacturer manualWater 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.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like P0.5-0.9: no call-out fees, no surprise bills.
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All 59 fault codes on the Powermax HE
Seeing a different code? Every code this model can display, in one place.
Related guides you might find useful
Boiler keeps losing pressure
Six most common causes of dropping pressure.
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Quarter turn on the valve, wait for water, then check the boiler pressure.
Read →Hot water works but heating does not
On a combi it is usually the diverter valve. On a system boiler, the motorised valve.
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