BoilerFaultCodesYour boiler has detected that a temperature sensor inside the exhaust pipe is faulty and needs replacing to ensure the unit operates safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flashing lamp, alternate with another lamp.
What causes this fault?
This fault occurs when the sensor responsible for monitoring the heat of the exhaust gases undergoes an electrical failure or provides an implausible reading. The most common reason is the internal degradation of the thermistor over time due to constant exposure to high temperatures, or moisture corrosion on the electrical connections. Without an accurate temperature reading, the boiler cannot ensure it is venting waste gases safely and will stop running as a precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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