What does the Ferroli LED4 (Flashing) fault code mean?

Your boiler is struggling to detect water flow or communicate internally, which is preventing it from starting up your heating or hot water.

How much does it cost to fix Ferroli error code LED4 (Flashing)?

Typical repair cost for the Ferroli LED4 (Flashing) fault is £150-300 including labour.

Central heating stand-by / Flow sensor fault / Main board check / Pump or Limit thermostat check

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Almost always a stuck diverter valve on combis.

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.