BoilerFaultCodesTechnical description
If the appliance is restarted it will make a gurgling noise prior to locking out
What causes this fault?
This fault occurs when the wastewater produced during the heating process cannot flow out of the boiler, causing the internal trap to overflow. The most common reason is a blockage in the external pipework, which prevents the unit from draining and effectively drowns the burner. This backup of water triggers a safety sensor to shut the system down to prevent internal damage.
This fault is extremely common during freezing winter temperatures, as the external condensate pipe can freeze solid and create a backup of water.
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.
Find a Gas Safe engineer
Search the official register →