BoilerFaultCodesYour boiler has lost its connection to your room thermostat, meaning it cannot receive instructions on when to turn the heating on.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Room thermostat communication error – disconnection or communication loss in room thermostat.
What causes this fault?
This fault occurs when the boiler's control board can no longer 'talk' to your room thermostat, usually due to a dropped signal or a hardware failure. The most common reason is simply that the thermostat batteries have run out, but it can also be caused by a faulty wireless receiver or loose wiring between the boiler and its controls.
This fault is frequently reported during the first cold spell of autumn when homeowners try to turn their heating back on after months of inactivity, only to find the thermostat batteries have drained.
DIY fix possible
Check if your wireless thermostat needs new batteries.Ensure the thermostat is within range of the boiler and there are no new obstructions.Check that the thermostat's receiver unit is powered on and plugged in correctly.
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A boiler cover plan would cover faults like E43 — 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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