BoilerFaultCodesTechnical description
Flow/return temperature sensor fault
What causes this fault?
This fault occurs when the boiler's internal computer receives conflicting information from the two sensors that measure water temperature entering and leaving the unit. It is usually caused by a sensor that has developed a chemical fault, or because the sensors have been physically swapped or installed on the wrong pipes. Because the boiler cannot accurately track how heat is moving through the system, it shuts down to prevent the primary heat exchanger from overheating.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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