BoilerFaultCodesTechnical description
Flow temperature too high, or temperature differential between primary and return too high
What causes this fault?
This fault occurs when the water inside the boiler heats up much faster than it can be moved away into your radiators. The most common cause is a blockage in the system or a failing pump that is no longer strong enough to keep the water circulating. Because the heat cannot 'escape' the boiler, the safety sensors shut everything down to prevent damage from overheating.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after months of inactivity, which can cause the internal pump to seize.
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.