BoilerFaultCodesTechnical description
Lockout temperature exceeded
What causes this fault?
This fault occurs when water cannot circulate through the boiler quickly enough to carry heat away, causing the internal temperature to reach a dangerous level. The most common reasons are a failed pump that isn't pushing water around, a blockage in the pipework, or air trapped within the heat exchanger. It acts as a safety 'trip' to prevent the appliance from being damaged by extreme heat.
This fault often appears when the heating is first turned on after summer, as the internal pump can seize up from months of inactivity.
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.
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