BoilerFaultCodesThe 4 most common faults
01
E01-204 High Engineer
Your boiler has detected a problem with the internal hot water heat exchanger, which means you may have no hot water running through your taps.
Full guide for E01-20402
E01-205 High Engineer
Your boiler has detected an issue with the domestic hot water heat exchanger, which usually results in a loss of hot water or improper water temperature regulation.
Full guide for E01-20503
E00-684 High Engineer
Your boiler is struggling to detect water flowing properly through its internal heating system, which temporarily stops it from working.
Full guide for E00-68404
E00-688 High Engineer
Your boiler is failing to detect the flow of water needed to provide hot water or heating.
Full guide for E00-688on the Biasi Garda
Plate heat exchangerDiverter valveFlow switchNTC thermistorFlow switch microswitchWiring harness
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Biasi shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue