Ariston MicroGENUS HE boiler error code A03

Hello,

My Ariston MicroGENUS HE boiler is displaying an error code A03. The boiler is not restarting as well. I have tried to restart it a number of times. Whenever I press the reset button on the boiler, this error code appears again & pump begins to run. Any suggestions what is wrong with the boiler & How to fix it?

Pat

Hi Pat,

You will see an error code A03 on the boiler’s display panel when the flow temperature surpasses 103 degree. The problem could be an overheated stat if boiler’s pump is running well. You can fix it easily by following these steps:

  • Firstly, you have to take out a left side board for easy access
  • Secondly, put the wire connection among overheat stat contacts & if your boiler begins working then, overheat stat has to be replaced

In majority of the cases, when users changed the contacts directly to overheat stat, their boilers work properly.