BoilerFaultCodesTechnical description
Outside sensor fault (if fitted) detected by diagnostic feature.
What causes this fault?
This fault occurs when the connection between the boiler and the external temperature sensor is broken or sending incorrect electrical signals. The most common reason is water ingress or corrosion inside the sensor casing located on your outside wall, or damage to the low-voltage wiring connecting it to the boiler.
This issue is often discovered during the first cold snap of autumn when the system attempts to use weather compensation to adjust your heating for the changing season.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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