BoilerFaultCodesYour boiler has detected a sensor error that prevents it from firing up safely, meaning your heating and hot water will not work until it is reset or repaired.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Lighting Sequence - Thermistor
What causes this fault?
This fault occurs when the boiler's internal computer receives an illogical or missing signal from the temperature sensor, which acts like the boiler's thermometer. The most common reason is that the sensor has physically failed or the electrical wiring connecting it to the main control board has become loose or damaged. Because the boiler cannot accurately gauge how hot the water is, it shuts down immediately to prevent overheating.
DIY fix possible
Turn the control knob to the 'Reset' position for 5-10 secondsTurn the control knob back to your desired temperature settingCheck if the boiler attempts to relight; if the flashing continues, you will need an engineer
Find a Gas Safe engineer
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A boiler cover plan would cover faults like LED 1 (RESET) Fast Flashing (8Hz), LED 2 (BURNER LIT) Fast Flashing (8Hz) Simultaneous — no call-out fees, no surprises.
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