BoilerFaultCodesYour boiler has lost water pressure and needs to be topped up to work properly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: All Combi Boilers
What causes this fault?
This fault occurs when the water pressure inside your heating system drops below the minimum level required for the boiler to operate safely. The most common reasons for this are a leak somewhere in your radiators or pipework, or simply having air trapped in the system after bleeding your radiators.
This code is frequently seen in autumn when homeowners turn their heating back on for the first time or bleed their radiators to prepare for winter.
DIY fix possible
Locate the filling loop (usually two small taps or a blue lever) under the boiler.Slowly open the taps until you hear water flowing and watch the pressure gauge.Close both taps tightly once the needle reaches 1.5 bar.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 108 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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