BoilerFaultCodesYour boiler has sensed that the internal water temperature has become dangerously hot, causing it to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The temperature captured by the flow temperature sensor exceeded 105°c
What causes this fault?
This fault occurs when water inside the boiler isn't moving away from the heat source quickly enough, causing it to overheat rapidly. The most common reason is a failed circulation pump or a blockage in the pipework that prevents the water from flowing. In some cases, a build-up of debris or limescale inside the heat exchanger can also restrict movement and trap heat.
This issue often surfaces during the first cold spell of autumn when the heating is turned on after being dormant all summer, which can cause internal pump parts to seize.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E5218 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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