BoilerFaultCodesTechnical description
Fault codes 3x appear if the boiler or flue system has developed a fault.
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that harmful exhaust gases are not being cleared from the system correctly. The most common reason is a failing fan that cannot spin fast enough or a blockage in the air pressure tubes that prevents the boiler from confirming the flue is clear.
This fault can be more common during periods of high winds, which can create back-pressure in the flue and interfere with the air pressure readings.
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.
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