BoilerFaultCodesYour boiler has likely stopped heating because a sensor that measures the temperature of the water leaving the unit has failed or become disconnected.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow Thermistor Fault
What causes this fault?
This fault occurs when the boiler's control board loses communication with the sensor responsible for monitoring the temperature of the water sent to your radiators. The most common reason is that the sensor has suffered an internal electrical failure or the wiring connecting it to the main circuit board has become damaged or loose.
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 F4 — no call-out fees, no surprises.
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Ideal Logic Combi ESP1 is discontinued — time for a new one?
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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