BoilerFaultCodesTechnical description
No heating demand from low voltage controls (clamp 7-8-9)
What causes this fault?
This status code physically triggers when the internal circuit board is successfully waiting for a signal but the external thermostat has failed to send one. The most common reason is that the thermostat has lost power or the physical wiring connecting your wall controls to the boiler has developed a fault. Effectively, the boiler is 'listening' for the command to start, but the controls are staying silent.
This code is frequently seen during the first cold spell of autumn when homeowners turn their heating back on only to discover their thermostat batteries died 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.