BoilerFaultCodesWhat the manual says
Manufacturer manualAir Pressure Switch neon status. If not lit, check fan and 240V supply to fan.
What causes this fault?
This fault occurs when the boiler's safety sensors cannot confirm that the fan is successfully pushing exhaust fumes out of the flue. The most common reasons are a buildup of debris in the fan or air tubes, or the mechanical switch itself failing to register the flow of air. Until the boiler is certain it can vent gases safely, it will prevent the burner from firing.
This issue is frequently seen during periods of high wind, which can create back-pressure in the flue that interferes with the sensitive air pressure switch.
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.
Avoid the next call-out bill
A cover plan would handle faults like APS neon lit: no call-out fees, no surprise bills.
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