| F.61 | Fault: gas valve operation. | The PCB cannot actuate/modulate the gas valve (coils shorted/open or defective wiring harness), so it does not open/close correctly; check coil resistance, wiring continuity, and control voltage during the ignition attempt. |
| F.62 | Gas valve disconnection delay. | The valve takes time to close or does not close tightly, leaving a flame signal after stopping; check tightness/closing time and ensure ionization disappears when the gas is cut off. |
| F.28 | Fault during appliance start-up: failed ignition attempts. | If the valve does not open or is improperly adjusted, gas does not reach the burner and no flame is detected; verify that it receives the opening command and check pressures (inlet and burner pressure) at startup. |
| F.29 | The flame goes out during operation and the next ignition attempt fails. | A valve that regulates poorly or gets stuck can cause a drop in flow/pressure and loss of ionisation during operation; check the stability of pressure downstream of the valve under load and the signal/power supply to the modulator. |
| F.27 | Safety shutdown: flame simulation. | If the valve does not close completely (internal leak), the electronics may 'see' a flame with the valve closed; check the valve's tightness and the absence of ionisation signal with the gas cut off. |
