| F.13 | Main PCB fault. | The PCB 0020063241 has an internal defect or poor connection with the interface/harness (e.g., fuse/relay/tracks or multipin connector). Check continuity of the wiring and voltages on the PCB; if the issue persists, replace the PCB. |
| F.63 | EEPROM (memory) error on the PCB. | Corruption/fault of the integrated EEPROM in the PCB 0020063241 prevents safe start-up. Check reset and stable power supply; if the error reappears, the prescribed action is to replace the PCB. |
| F.64 | Fault in the electronics/sensor (involves PCB electronics). | Short circuit in flow/return NTC or fault in the electronics of PCB 0020063241 in the reading channel. Check NTC/wiring; if they are correct, the fault lies in the electronics of the PCB. |
| F.65 | Electronics temperature too high / electronics fault. | Overheating of the electronic module or internal defect in the PCB 0020063241. Check ventilation/location and temperature in the electronic box; if the overheating is not external, replace the PCB. |
| F.67 | Electronic system fault/implausible flame signal. | Fault in the flame detection circuit integrated in the PCB 0020063241 or in its electronic processing. Check electrode/wiring/ground; if they are correct and the signal remains erratic, the fault is with the PCB electronics. |
| F.70 | Invalid boiler identification / incompatible interface with the main PCB. | Product code mismatch or incompatibility between display/interface and PCB 0020063241. Verify and reconfigure appliance code (technical menu d.93); if it does not match or accept coding, replace the incompatible module or the PCB. |