Biasi boiler error code 01
This error code signals that the flame sensor electrode is not working. Check it for corrosion or other damage. Since it is a low volt device, rust can create resistance and make it insensitive to flame. In this case, the electrode needs to be replaced. Also, there may be a wire or connection problem.
Biasi boiler error code 04
This code appears when there is not enough water in the boiler or there is a circulation problem.
How to fix it
To clear the code, refill and reset the boiler. Check pressure and make sure it is around 1.5 bar, and the boiler is filled properly. Fill it via the external filling system.
If pressure is all right, check the circulation. Most likely, there is a pump problem. Check the pump and, if necessary, repair or replace it.