BoilerFaultCodesWhat the manual says
Manufacturer manualAir fault lock
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that air isn't flowing correctly through the unit to safely remove waste gases. The most common reason is a failing fan that can no longer spin at the required speed or a blockage in the pipes that lead to the outdoors. Because the boiler cannot guarantee that harmful fumes are being moved away safely, it will refuse to ignite as a protective measure.
High winds or extreme stormy weather can occasionally cause this fault by creating back-pressure in the flue pipe that prevents the fan from venting correctly.
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 03: no call-out fees, no surprise bills.
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