BoilerFaultCodesTechnical description
Return temperature sensor overheating due to a blocking fault or a lockout error – try resetting the boiler
What causes this fault?
This fault occurs when the water traveling back into the boiler from your radiators is at a higher temperature than the system expects, which usually signals a circulation problem. The most common reasons are a pump failure that isn't moving water fast enough, or a blockage caused by internal debris or air trapped in the system. As a safety measure, the boiler shuts down to prevent the internal components from being damaged by this excessive heat.
This issue is more common during the first cold spell of autumn, as circulation pumps can seize up after being inactive over the summer months.
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.