Your boiler has detected a critical internal fault with the burner system that regulates the fuel supply, meaning the appliance cannot ignite safely.

Burner Injector – Propane Stereomatic, Type 7, Rs1/8 3.1mm

What causes this fault?

This fault occurs when the boiler detects an issue with the components that deliver and ignite the gas at the burner, often due to a blockage or wear in the injector. Over time, carbon build-up or a failing gas valve can prevent the correct fuel-to-air mixture from reaching the ignition point, causing the system to shut down for safety. It essentially means the boiler can no longer guarantee a stable and controlled flame.