BoilerFaultCodesWhat the manual says
Manufacturer manualInsufficient water pressure, Air in boiler, or the pressure in the boiler is low.
What causes this fault?
This fault occurs when the internal water pressure drops below the minimum level required for the boiler to circulate heat safely. The most common reason is a small leak in the radiator network or air being released through the valves, which gradually reduces the volume of water in the system.
This issue often surfaces when the heating is turned back on for autumn, as the transition from cold to hot water can expose minor leaks or highlight air trapped in the radiators.
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.