Your boiler's internal thermometer is reporting a temperature that doesn't make sense, causing the system to shut down for safety.

Fault: Flow sensor - Flow temperature sensor returns implausible values

What causes this fault?

This fault occurs when the boiler's internal computer receives conflicting information from the temperature sensor on the main pipe. The sensor may have developed an electrical failure, or it has become unclipped from the pipe, preventing it from accurately reading how hot the water is. To prevent the system from dangerously overheating, the boiler shuts down until the sensor is repaired or replaced.