| F04 | Flue thermostat anomaly. | Incorrectly configured card parameters or a fault in the PCB itself cause incorrect thermostat management; verify PCB parameters and, after ruling out thermostat/wiring, reprogram or replace the PCB. |
| F05 | Flue pressure switch anomaly (the contact does not close). | The PCB may be the cause due to 'misconfigured board parameter' or 'board anomaly' (reading/management of the pressure switch/fan); check the fan, pressure switch, and wiring, and if they are correct, reconfigure or replace the PCB. |
| F07 | Flue pressure switch anomaly (stuck contact). | Parameter error of the card or fault of the PCB itself can force an incorrect reading of the pressure switch; check the pressure switch and wiring, and if they are fine, review/program or replace the PCB. |
| A23 | The nominal water pressure in the installation is not reached within 4 minutes. | The logic of the PCB triggers the code if the thresholds/parameters are incorrectly programmed; check the pressure and water pressure switch, and if they are correct, adjust the PCB parameters or replace the PCB if it does not allow configuration. |
| A24 | Four fillings in 24 hours. | The counter/thresholds managed by the control board may be misconfigured or the PCB may be faulty; check for leaks/pressure and, if everything is correct, reprogram the board parameters or replace it. |
| A02 | Flame signal present with burner off. | False ionization reading at the PCB input ('board anomaly') generates the code; check electrode/ground/wiring and, if they are OK, the fault is in the PCB (ionization input). |
| F34 | Supply voltage below 180 V. | If the network is at 230 V and the fault persists, the measurement/power circuit of the PCB (e.g., transformer/capacitors like C21) is usually degraded and the board 'reads' low voltage; verify actual 230 V, secondary voltages/28 V of the board and repair or replace the PCB. |