| 134 | Gas valve blocked. | The gas valve is stuck or its coil is not operating, preventing opening/modulation and ignition. Check the control signal and voltage at the valve, coil resistance, and gas supply pressure during demand. |
| 15 | Gas valve control error. | Fault in the valve control (loose connector, damaged wiring, or open coil), so the PCB cannot actuate the valve. Check continuity from the PCB to the valve connector and the presence of control voltage during the ignition attempt. |
| 09 | Gas valve connection error. | The boiler detects a loss of communication/electrical connection with the valve (loose connector, damaged harness). Check the fixation of connectors, continuity of cables between the PCB and valve, and absence of shorts/opens. |
| H.01 .00 | Temporary communication failure between the gas valve and the PCB. | Intermittencies in the valve (connector/coil) cause temporary loss of communication. Check terminals and ground, clean/adjust terminals, and check control/modulation signal to the valve during start-up. |
| E.02 .17 | Permanent communication failure between the gas valve and the boiler PCB. | Fault in the valve or its harness causes permanent loss of communication. Check continuity of the wiring, power supply/output of the PCB, and coil resistance; if there is a control board and the valve does not respond, replace the valve. |