BoilerFaultCodesYour boiler's gas valve is not closing properly because of debris, which could lead to an unsafe gas buildup within the unit.
Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.
Technical description: Dirt on valve seat of Honeywell control.
What causes this fault?
This fault occurs when microscopic debris or grit becomes trapped within the gas valve mechanism, preventing it from forming a tight seal when the boiler switches off. Because the valve cannot close fully, a small amount of gas continues to leak into the combustion chamber, which creates a significant safety risk. The most common reason is the age of the internal components or particulates entering from the gas supply pipework.
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 D(2) — no call-out fees, no surprises.
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