BoilerFaultCodesTechnical description
Burner does not start. Outside sensor fault (short circuit or lead break).
What causes this fault?
This fault occurs when the boiler loses connection with the temperature sensor mounted on the external wall of your home. It is physically caused by either a terminal failure inside the small plastic sensor box or damage to the electrical cable connecting that sensor back to the boiler's main control board. Without this reading, the boiler cannot calculate the correct water temperature and prevents the burner from firing as a safety precaution.
This fault is more common during autumn and winter, as heavy rain or freezing conditions can accelerate corrosion within the sensor casing or cause water ingress in the wiring.
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.