| A01 | The burner does not ignite. | If the gas valve is faulty or not powered, it does not allow gas to pass to the burner and there is no ionisation. Check voltage to the modulator/coils and ensure there is pressure downstream of the valve. |
| A09 | Gas valve anomaly. | Electrical or mechanical fault of the valve (coil/modulator open, stuck). Check coil continuity and opening sequence from the PCB; replace if it does not operate. |
| A16 | Gas valve anomaly. | Recurrent issue with the valve (wiring/modulation or damaged valve). Check the modulator wiring and operation; if it does not respond, replace the valve. |
| F50 | Gas valve anomaly (modulation actuator). | Interruption/fault in the modulator wiring or damaged modulating coil; the valve does not modulate. Measure continuity/resistance of the modulator and check for signal presence from the PCB. |
| A62 | There is no communication between the control board and the gas valve. | Break/defect in the valve harness or valve not responding to the control board. Check connectors and continuity; if the bus/command arrives and the valve does not respond, replace it. |
