BoilerFaultCodesTechnical description
Delay mode due to lack of water in system (~20 mins.)
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the water is heating up far too quickly or isn't moving through the unit fast enough. The most common reasons are a build-up of sludge blocking the heat exchanger, a pump that is failing to circulate the water, or simply air trapped within the system. To prevent internal damage from overheating, the boiler enters a temporary waiting period to allow the components to cool down.
This issue is most frequent in autumn when the heating is turned back on after a long summer break, as stagnant debris in the pipes can settle and cause blockages.
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.