BoilerFaultCodesTechnical description
If the boiler is not lit when a hot tap is opened this could mean there is a lack of water flow or possible flow switch problem
What causes this fault?
This fault occurs when the boiler fails to detect water moving through the pipes when you turn on a hot tap. The most common reason is that the internal sensor used to trigger the burner has become stuck or damaged, preventing the boiler from knowing there is a demand for hot water. In some cases, a perished rubber diaphragm or a blockage within the unit is stopping the mechanical parts from moving correctly.
This fault is slightly more common in winter when incoming mains water is much colder, which can cause internal rubber components to become less flexible and more prone to failure.
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.