Ariston Clas 30 HE error code 303

Hi Folks,

My newly bought and installed Ariston Clas 30 HE boiler is showing a 303-error code since last night on its control board. I have restarted the boiler but the problem persists. Is something serious? The boiler is under warranty, should I replace it or call a service center? Please help me accordingly.

Thanks a lot


Hi James,

According to the Ariston boiler’s user manual, an error code 303 means that, the printed circuit board of the boiler is not working properly. A PCB is considered as the most expensive and important component because it accepts & provides signals to the electrical parts of the boiler. It is better to call an expert Ariston boiler engineer for detailed investigation. Sometimes, a boiler engineer can repair the weak electrical system & connections to a printed circuit board.