BoilerFaultCodesTechnical description
CH flow NTC sensor defective (short circuit/interruption).
What causes this fault?
This fault occurs when the internal sensor responsible for tracking the temperature of water leaving the boiler fails to send a reliable signal to the main control board. The most common reason is that the sensor's internal components have worn out over time or a loose electrical connection has developed within the wiring harness. Because the boiler no longer knows how hot the water is, it shuts down as a safety precaution to prevent overheating.
This fault often appears at the start of autumn when the heating system is first turned on after being idle all summer, which can stress aging electronic components.
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.