| F.61 | Gas valve activation error | The PCB controls the gas valve coil; if the driver/output on the board is faulty, the valve does not receive a command and cannot be activated. Check the voltage at the valve during demand and, with wiring/valve OK, check or replace the PCB. |
| F.62 | Gas valve disconnection delay | The switching element of the PCB that cuts the valve may become 'stuck', causing a delayed shutdown. Check for voltage presence at the valve after shutdown and rule out parasitic light/gas leak; if it persists, check the PCB. |
| F.63 | Fault: EEPROM | Memory error in the PCB (corruption/defect). If it persists after a reset and sensors/wiring are correct, replace/program the PCB according to the manual. |
| F.64 | Electronic fault / NTC | If the flow/return NTC sensors and their harness are correct, the fault is in the measurement/ADC stage on the PCB. Check the ohms of the NTC at the terminals and continuity; with plausible readings, the cause is the control board. |
| F.65 | Fault: PCB temperature | Overtemperature or PCB electronics fault (thermal sensor/power stage). Check for external thermal influences and dissipation; if normal, check or replace the PCB. |
| F.67 | Fault: electronics/flame | Flame signal not plausible due to a fault in the flame control electronics of the PCB. Check electrode, grounding, and ionization microamperage; with correct readings, the PCB is responsible. |
| F.70 | Invalid appliance code (DSN: "Device Specific Number") | It appears after replacing the PCB (and/or display) without reprogramming the DSN of the model; the board remains without valid identification. Check in diagnostic d.93 and configure the correct DSN; if it doesn't accept, the board is either not suitable or is defective. |
