BoilerFaultCodesYour boiler has detected an issue with how it clears exhaust fumes, so it has shut down as a safety precaution to prevent a build-up of waste gases.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Pressure differential switch on the flue system to check the fan's operation (does not allow ignition)
What causes this fault?
This fault occurs when the boiler's internal safety sensor detects that the fan isn't moving air through the flue correctly. The most common reasons are a blockage in the flue pipe, a build-up of dirt in the fan, or a small component called the air pressure switch failing to register the airflow.
This issue can be more common during periods of high winds, which can create back-pressure in the flue and interfere with the sensitive pressure readings.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 22 — no call-out fees, no surprises.
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