BoilerFaultCodesTechnical description
Check room thermostat batteries
What causes this fault?
This fault occurs when the boiler is unable to receive a signal from your heating controls, meaning it doesn't know whether it should be heating your home or not. The most common reason is that the batteries in your wall-mounted thermostat have run out of power, though it can also happen if the wireless signal is being blocked by a new obstacle or if the receiver on the boiler itself has developed a fault.
This fault is frequently seen at the start of autumn when homeowners turn their heating back on for the first time and discover their thermostat batteries have drained over the summer.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.