BoilerFaultCodesYour boiler has detected an issue with the heat exchanger's temperature sensors, causing the system to lock out 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: GO TO FRAME 76
What causes this fault?
This fault occurs when the boiler's internal sensors detect an unusual temperature difference between the water entering and leaving the heat exchanger. The most common reason is a blockage or poor water flow through the system, though it can also be triggered if one of the temperature sensors has become faulty or unclipped. To prevent damage, the boiler's computer shuts the system down until the issue is resolved.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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