| E01 | Lockout due to ignition fault | The ignition/modulation board may not excite the ignition transformer or properly power the gas valve; if the electrode, wiring, and gas are OK and there is no discharge/commands from the board, the PCB is faulty. |
| E03 | Fan fault | If with demand the PCB does not deliver 230 V to the fan (output from PCB/relay K4), the fault is with the PCB; check the voltage at the fan output terminals and, if there is none, replace the PCB. |
| E04 | Generic anomaly of the boiler PCB | The self-diagnosis of the PCB detects an internal anomaly; after checking the safety thermostat and the flue pressure switch, the solution indicated by the manufacturer is to replace the PCB. |
| E15 | Configuration error | Configuration/self-recognition fault of the boiler by the PCB; if the recognition wiring (e.g. flue pressure switch) is correct, the PCB must be replaced. |
| E20 | Lockout due to parasitic flame | The ionisation electronics on the PCB detect spurious flame current; if the electrode and wiring are correct, the manufacturer advises replacing the PCB. |
| E24 | Anomaly of the control panel | If the panel keys work mechanically and no keys are stuck, the fault is in the reading/management on the PCB; the official procedure is to replace the PCB. |
| E31 | Remote Control Communication Loss | If the wiring to terminals 41–44 and the CAR control are fine, the loss of communication is due to the PCB; replace the control board after verifying polarity and dedicated line. |
| E37 | Low supply voltage | If the network is within 230 V ±10% and fuses/cables are OK but the error persists, the measurement/management on the PCB is defective; replace the control board. |
| E44 | Lockout due to maximum time of partial opening of the gas valve | Gas valve control fault by the PCB (maintains excessive partial opening); if the event is recurrent after verifying modulation and calibration, replace the PCB. |
