BoilerFaultCodesTechnical description
High water pressure with temperatures reaching
What causes this fault?
This fault occurs when the internal water pressure becomes too high while the boiler is running, often caused by a faulty filling valve that is letting too much water into the system. It can also happen if the expansion vessel, which manages pressure changes as water heats up, has failed or lost its air charge. When these two factors combine, the boiler shuts down to prevent internal components from being damaged by the excessive force.
This fault is more common during the first cold spell of autumn when the heating is turned on for the first time in months, putting sudden stress on the expansion vessel.
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.