BoilerFaultCodesTechnical description
Should the appliance not light, check it is not in the overheat lock-out state, by pressing the re-reset button on bottom right hand side of the control box.
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering a safety switch to prevent damage. The most common reasons are a pump failure that stops water from moving through the system or a build-up of debris blocking the internal heat exchanger. It can also be caused by a faulty sensor misreading the temperature even if the boiler isn't actually too hot.
This fault is more common in autumn when heating systems are turned back on after a long summer break, often revealing a circulation pump that has seized during the idle 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.