BoilerFaultCodesWhat the manual says
Manufacturer manualFlow Temperature Overheat Lockout
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature, causing the system to shut down for safety. The most common reasons are a pump failure preventing water from moving through the system or a blockage caused by a build-up of sludge and debris. It can also be triggered by a faulty sensor that is incorrectly reporting the water temperature to the control board.
This fault is more common in autumn when homeowners turn their heating back on after a long summer break, as the internal pump can often become seized or stuck during periods 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.
Avoid the next call-out bill
A cover plan would handle faults like L1: no call-out fees, no surprise bills.
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