BoilerFaultCodesTechnical description
Appliance is within the waiting period of the operation block function due to water shortage (VL- RL spread too big)
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the heat being produced isn't being carried away by the water fast enough, causing a rapid temperature spike. The most common reasons are a failing pump that can't push the water around or a blockage caused by a buildup of sludge and debris within the system. It can also be triggered if air is trapped in the pipes or if the radiator valves are all closed, preventing any flow.
This fault often appears at the start of winter when the heating is turned on for the first time after summer, as pump components can seize during long periods of inactivity.
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.