BoilerFaultCodesYour boiler is having trouble 'talking' to your smart thermostat or external heater controls, meaning it may not receive instructions to turn on or off.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: OpenTherm (OT) communication error
What causes this fault?
This fault occurs when the digital connection between your external thermostat and the boiler's internal computer is broken or interrupted. The most common reasons are loose wiring connections at either end of the control cable or a electronic synchronization failure between the two devices.
DIY fix possible
Check that your smart thermostat or wall controller is powered on and has working batteries.Ensure the thermostat bridge or hub is plugged in and connected to your Wi-Fi.Try restarting your boiler at the main isolation switch to reset the connection.
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
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