BoilerFaultCodesWhat the manual says
Manufacturer manualAir flow proving fault - that is fan or air pressure switch
What causes this fault?
This fault occurs when the boiler's internal safety sensors fail to detect the constant flow of air required to safely expel exhaust gases. The most common cause is a failing fan motor that cannot spin fast enough, or a blocked pressure tube that prevents the system from confirming the fan is working correctly.
This issue can occasionally surface during periods of high winds, as strong gusts can cause back-pressure in the flue that disrupts 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 Neon 3 lit (No): no call-out fees, no surprise bills.
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