What does the Biasi 4 + fault code mean?

Your boiler has detected that the water pressure is either too low or too high, or the water is not moving through the system correctly.

How much does it cost to fix Biasi error code 4 +?

Typical repair cost for the Biasi 4 + fault is £100-280 including labour.

Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.

Pump circulation failure, insufficient system pressure or pressure above 3 bar, water pressure sensor not connected.

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

Six most common causes of dropping pressure.

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.