Biasi M90 Combi Boiler 03 Error Code

Hello Folks,

My four years old Biasi M90 combi boiler is showing a 03-error code. After reading the Boiler’s user guide, I came to know that 03-error code means “General Lockout”. What does it mean? How to fix it immediately as the boiler is not working.

Thanks for the Guidance


Hi Smith, you are right 03 Error code deals with boiler’s general lockout. A lockout is a shutdown process that is triggered when a boiler fails to work under certain tolerances. Some Common faults, which lead to boiler’s lockouts, are as follows:

  • Faulty pump
  • No power
  • Boiler overheating
  • System blockage
  • Blockage in the heat exchanger
  • High/low pressure of water
  • Ignition failure

Do check these faults in your boiler. Biasi Combi boiler has a reset button, you have to press & hold this button in order to reset your boiler after the lockout. I hope, this information will work for you.