BoilerFaultCodesYour indoor and outdoor units are failing to speak to each other, which has caused your heating system to stop working.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No connection Outdoor PCB to Indoor PCB
What causes this fault?
This fault occurs when the data link between your indoor control unit and the outdoor heat pump unit is broken. The most common reason is a loose or damaged connection in the communication wiring, though it can also be caused by a power failure at the outdoor unit or a faulty circuit board preventing messages from being sent.
This fault can sometimes emerge after heavy storms or high winds if debris or moisture has caused a loose connection or damaged the exposed wiring between the units.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like H0 — 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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