Your boiler is failing to light the pilot flame or detect a steady flame, meaning it cannot start the heating process.

Ignition, pilot or flame proving fault.

What causes this fault?

This fault occurs when the boiler attempts to start up but cannot establish or maintain the small pilot flame needed to ignite the main burner. The most common reasons are a blocked pilot hole preventing gas flow or a worn-out sensor that can no longer tell the boiler it is safe to stay on. In some cases, the gas valve may be failing to release the fuel required to start the ignition process.