Your boiler is busy prepping for a heating cycle by checking its internal sensors and clearing the flue, but if it stays stuck on this display, it may be failing to light.

What causes this fault?

This code appears when the boiler begins its startup sequence, spinning up the fan and water pump to ensure the system is safe to ignite. If the boiler becomes stuck on this screen, it usually means the internal controls are waiting for a signal to proceed that isn't arriving. In many cases, this is caused by a minor electrical communication issue or a component failing to reach the necessary speed to trigger the next step.