BoilerFaultCodesYour boiler has detected that the exhaust gases are getting too hot, causing the fan to run at full speed to protect the system from damage.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flue gas probe error for having exceeded the temperature limit (with this error, the fan operates at max.)
What causes this fault?
This fault occurs when the internal sensors detect that the exhaust gases have reached a dangerously high temperature, which is often a sign that heat isn't being transferred effectively to the water. The most common reasons are a heavy buildup of limescale or debris inside the heat exchanger, or a physical blockage within the flue pipes preventing proper ventilation.
This issue often comes to light during the first cold spell of autumn or winter when the boiler is required to run at maximum output for long periods.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like E48 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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