BoilerFaultCodesTechnical description
Primary system water pressure too low
What causes this fault?
This fault occurs when the water level inside your heating system drops below the minimum required amount, making it unsafe for the boiler to fire up. The most common reasons for this drop are a small leak in the pipework or radiators, or the need to bleed air from the system after a period of inactivity. If the pressure continues to drop after you refill it, a component inside the boiler like the expansion vessel may be failing.
This code is frequently seen in autumn when homeowners turn their heating back on for the first time, as small leaks or trapped air can cause the pressure to dip during the summer months.
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.