BoilerFaultCodesYour boiler has lost connection with the sensor that monitors the outdoor temperature, which might cause it to heat your home inefficiently.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Outside sensor short circuit
What causes this fault?
This fault occurs when the boiler can no longer receive a clear signal from the sensor located on your outside wall. The most common reasons are water getting into the sensor housing, or the electrical wiring becoming damaged or corroded due to exposure to the elements. Without this data, the boiler cannot automatically adjust its temperature based on how cold it is outside.
This issue often surfaces during periods of heavy rain or high winds, which can force moisture into the sensor casing or damage external cabling.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like F15 — no call-out fees, no surprises.
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