BoilerFaultCodesTechnical description
Outside temperature sensor error (S4)
What causes this fault?
This fault occurs when the boiler is unable to receive a reliable signal from the small sensor mounted on the outside of your property. The most common reasons are that the sensor’s internal components have corroded due to exposure to the elements, or the electrical wiring connecting the sensor to the boiler has become damaged or loose.
This fault is often more noticeable during autumn and winter when the boiler needs to calculate higher flow temperatures to keep the home warm.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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