BoilerFaultCodesTechnical description
Boiler locked by external switching contact
What causes this fault?
This fault occurs when an external device connected to the boiler sends a signal to stop it from firing for safety or control reasons. The most common cause is a full condensate pump that has triggered a safety overflow switch, or a smart thermostat that has lost its connection. It can also be triggered by a faulty wiring center or depleted batteries in your wall controller.
This fault is more frequent during freezing winter temperatures, as frozen external pipes can cause condensate pumps to backup and trigger the safety shut-off.
DIY fix possible
Check that your room thermostat is turned up higher than the current room temperature.Ensure your smart heating hub and internet router are both powered on and connected.Replace the batteries in your wireless room thermostat or wall controller.Check if a safety device, like a condensation pump, has overflowed and tripped the switch.