Technical description
Short circuit: Cylinder temperature sensor. NTC sensor defective, short circuit in the cable harness, cable/housing
What causes this fault?
This fault occurs when the electrical signal from the hot water temperature probe is interrupted, usually because the sensor has failed internally. The most common reason is that the sensor has developed a physical short circuit or the wiring connecting it to the main control board has become damaged or loose. Because the boiler can no longer tell how hot the water is, it stops heating the cylinder as a safety precaution.
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.