| 50-59 | PCB (control board) fault/anomaly. | The self-diagnosis associates these codes with PCB faults (damaged components, cold solder joints, fuse or relays). Check voltages 230 V and 5/12 V on the board, continuity of fuses, and if it persists, replace or reprogram the PCB. |
| COM | Electronic communication loss with the boiler PCB (>30 s). | The main PCB stops communicating with the panel/interface (bus). Check the wiring/bus, voltages of the PCB and the interface; if communication remains down, the cause is usually the PCB itself and it should be replaced. |
| E056 | Absence of communication between microprocessor/PCB. | Microcontroller or communication circuit fault on the PCB. Check stable power supply, ground, and bus; if the error persists with correct wiring/UI, replace the board. |
| E052 | Hardware error outside threshold (electronics self-test). | The PCB detects internal parameters out of range (hardware). Confirm voltages and network noise; if it reappears after reset and with correct power supply, replace the control board. |
| FWER | Incompatible firmware version (the boiler continues to operate without display/buttons). | Firmware incompatibility between the control board and the interface (common after replacing one of them). Check/update matching versions or install the board with the correct reference/firmware. |