BoilerFaultCodesTechnical description
CH system pressure less than 0.5 bar / water pressure switch fault
What causes this fault?
This fault occurs when the internal sensor detects that the water pressure has dropped below the minimum level required for the boiler to operate safely. The most common reason is a slow leak somewhere in your radiators or pipework, or simply that the expansion vessel needs recharging. Without enough water pressure, the boiler cannot circulate heat effectively and will shut down to prevent internal damage.
This fault is frequently seen in autumn when the heating is turned on for the first time after summer, as air can trapped in radiators and settled leaks become apparent.
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.