| F.28 | Fault: unsuccessful ignition on start-up | The PCB may fail (defective electronics) or have the multi-connector improperly plugged in, preventing ignition management; check power supply and ground connections, continuity of the harness, and seating of the multipin on the PCB before replacing it. |
| F.61 | Gas valve activation error | The PCB does not correctly control the gas valve (electronic fault) or shows a fault/short circuit in the driver; check the control output from the PCB, continuity/insulation towards the coils, and if there is no correct signal, replace the PCB. |
| F.62 | Gas valve disconnection delay error | An electronic fault in the PCB may maintain a delayed shutdown command or late flame detection; check the control signal at the gas valve terminals, and if the shutdown command persists without an external cause, replace the PCB. |
| F.63 | EEPROM fault | Fault in the PCB memory (EEPROM) or data corruption; confirm with resets/auto-test, check for stable voltages, and if the fault persists, replace the PCB. |
| F.64 | Electronic fault / NTC | The electronics of the PCB are declared faulty or misinterpret sensors due to an internal error; check sensors/harness and, if they are correct, the cause is the PCB. |
| F.65 | Fault: PCB temperature | The PCB detects overheating or a fault in its internal thermal circuit; check ventilation/environment and temperature in the electronic box, and if it reappears without an external cause, replace the PCB. |
| F.67 | Fault: electronics/flame | The ionisation signal is not plausible due to a fault in the flame circuit on the PCB; check the electrode/wiring and, if the signal remains abnormal with correct hardware, the cause is the electronics of the board. |
| F.70 | Invalid product code (DSN) | The display and/or printed circuit board has been replaced without reconfiguring the product code/DSN; check with the service menu and reprogram the code or, if not possible, replace/configure the correct PCB. |