BoilerFaultCodesWhat the manual says
Manufacturer manualInsufficient water pressure, Air in boiler. Pressure in the boiler is low.
What causes this fault?
This fault occurs when the internal sensors detect that the water level inside your central heating system has dropped below a safe threshold. The most common reason is a slow leak from a pipe or radiator, though sometimes the pressure drops simply because air has escaped through the system's vent.
This issue is frequently seen in autumn when the heating is turned on for the first time after summer, as stagnant air bubbles move through the system or old seals begin to weep.
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 04: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.